Tag Archives: Energy efficiency

Energy-efficient Design with Masonry Construction

Photo courtesy Richard Filloramo

Photo courtesy Richard Filloramo

by Richard Filloramo, B.S. Arch, A.S. CT, and Chris Bupp

Masonry materials and wall assemblies, with their inherent thermal mass characteristics, provide designers with many options to achieve efficient designs. Architects and engineers have to make new decisions to reduce their projects’ energy consumption, requiring close collaboration and coordination with building and energy codes, along with construction documents.

The most significant code changes include increased R-values for non-mass opaque walls (e.g. cold-formed metal framing), requirement options for continuous insulation (ci), a need for continuous air barriers, R-value reductions for thermal bridging, and three paths for building energy design.

The 2015 International Building Code (IBC), in Chapter 13 (“Energy Efficiency”) states buildings shall be designed in accordance with the 2015 International Energy Conservation Code (IECC). The latter code’s Chapter 5 (“Commercial Energy Efficiency”) enables designers to use either IECC or American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) 90.1-2013, Energy Standards for Buildings except Low-Rise Residential Buildings.

This article examines examples of energy design using ASHRAE 90.1-2013, Section 5 (“Building Envelope”), and also notes requirements from ASHRAE 90.1-2010 (per the 2012 IBC and IECC). Designers may select ASHRAE 90.1 over IECC Chapter 5 because it provides a more in-depth, comprehensive, and complete approach to building energy design.

First, a designer must determine the climate zone for the building location by using the ASHRAE appendix Figure B1-1 map and tables depicted in Figure 1. For example, all of Connecticut is in Climate Zone 5, while New York encompasses three Climate Zones—Table B1-1 indicates the appropriate zone for the various towns, cities, and counties.

Next, the architect will select a compliance path based on the climate zone, space conditioning category (ASHRAE 5.1.2) and class of construction from ASHRAE Section 5.2 (“Compliance Paths”), as shown in Figure 2. The building envelope must comply with Sections 5.1, 5.4, 5.7, and 5.8, along with either:

● Section 5.5 (“Prescriptive Building Design Option”), provided the fenestration area does not exceed the maximum allowed in Section 5.5.4.2 (40 percent in ASHRAE 2012); or
● Section 5.6 (“Building Envelope Trade-off Option”).

Projects may also use Energy Cost Budget Methods, Section 11, as described in ASHRAE 90.1, Section 5.2.2. This article focuses on the first option—the prescriptive path (Section 5.5)—and also discuss Section 5.4.3 (“Air Leakage and Continuous Air Barrier Requirements”).

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The prescriptive path
While larger commercial, institutional, and municipal buildings may use some form of energy modeling (Section 5.6 or Section 11), the examples shown using the prescriptive path demonstrate basic compliance with the code and assist at understanding assembly R-values for various building envelope wall systems. The prescriptive path method provides an efficient means to establish the required insulation in a wall that can be used in a final design or in a preliminary study.

ASHRAE 90.1, Section 5.5 provides building envelope design tables for all climate zones for either non-residential or residential construction. (The latter includes dwelling units, hotel/motel guest rooms, dormitories, nursing homes, patient rooms in hospitals, lodging houses, fraternity/sorority houses, hostels, prisons, and fire stations.1)

To comply with the prescriptive path for Opaque Areas (Section 5.5.3) a designer may select from one of the two following methods:

● Method A: minimum R-value insulation requirements; or
● Method B: maximum U-factor (or R-value) for the entire assembly (Figure 3).

The second method is a more efficient means to configure a masonry wall assembly.

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Building envelope basics
An essential component of wall design—masonry or otherwise—is drainage capability and ventilation air space. IBC Chapter 14 (“Exterior Walls”) requires the exterior wall envelope be designed and constructed in such a manner as to prevent the accumulation of water within the wall assembly by providing a water-resistive barrier behind the exterior veneer, and a means for draining water that enters the assembly to the exterior. While there are exceptions, this requirement is essential to successful design.

Ventilated air space is also essential to keep the wall components dry, which prevents deterioration of wall components and water infiltration. Providing a sufficient air space in accordance with industry standards has become more difficult as new energy requirements can increase insulation thickness—owners are apprehensive to allow thicker walls that will encroach on the net interior building area.

The 2015 IBC references the Masonry Standards Joint Committee (MSJC)’s Building Code Requirements for Masonry Structures (i.e. The Masonry Society [TMS] 402-13/American Concrete Institute [ACI] 530-13/American Society of Civil Engineers [ASCE] 5-13) and Specifications for Masonry Structures (TMS 602-13/ACI 530.1-13/ASCE 6-13). In Chapter 12 (“Veneers”), Sections 12.2.2.6.2, 12.2.2.7.4, 12.2.2.8.2, and 6.2.2.8 states:

A 1-in. (25.4 mm) minimum air space shall be specified.

However, this is a code minimum and not recommended. Standard construction tolerance for the veneer and backup of ± 6 mm (¼ in.) variation from plumb can leave a resulting 12-mm (½-in.) air space, which is unacceptable. Industry organizations such as the International Masonry Institute (IMI), Brick Industry Association (BIA), and National Concrete Masonry Association (NCMA) recommend a 50-mm (2-in.) minimum air space. With these new increased requirements for higher R-values and sometimes thicker insulation, a 38-mm (1 ½-in.) air space would be sufficient. If air spaces are smaller, it may be advisable to provide continuous, full-height drainage mat in the wall cavity to assist with drainage and air flow and prevent mortar bridging (Figure 4).

It should also be noted MSJC sets the maximum cavity space at 114 mm (4 ½ in.) based on prescriptive design. Cavity spaces exceeding this size are acceptable, provided engineering calculations are provided for the masonry veneer ties. Recently, newer and stronger masonry ties, anchors, and fasteners have been developed that provide sufficient strength for wider cavities.

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Understanding the prescriptive path
An example of ASHRAE Table 5.5.5 for Building Envelope requirements in Zone 5 is shown in Figure 5. A masonry mass wall (masonry veneer and concrete masonry unit [CMU] backup), non-residential, under Method B (first column), would require an assembly U-factor of U-0.090—this equals R- 11.11(R=1/U). It should be noted there was no increase in the required R-value for mass walls from the R-11.11 in 2012 IBC/IECC/ ASHRAE 2010).

The same mass wall under Method A (second column) would require continuous insulation with a minimum R-value of R-11.4. A steel-framed wall (masonry veneer and steel stud backup) under Method B requires an assembly U-factor of U-0.055—this equals R-18.18. It should be noted this is a significant increase from R-15.63 required in the 2012 IBC/IECC/ASHRAE 2010). The same stud wall under Method A would require R-13 insulation in the stud space and R-10 continuous insulation (R-13 / R-7.5 ci in 2012 IBC/IECC ASHRAE 2010).

Stud wall assemblies have much higher requirements (i.e. R-7.07) than masonry mass walls because of the benefits of thermal mass, which are now quantified in the national energy codes. Advantages of thermal mass masonry include:

● reduction of temperature swings;
● moderation of indoor temperature;
● storage of heating/cooling for later release (Figure 6);
● reduction and shift of peak heating and cooling loads to non-peak hours; and
● passive solar design.

(Designers should check National Fire Protection Association [NFPA] 285, Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-load-bearing Wall Assemblies Containing Combustible Components, and manufacturer’s requirements when specifying combustible insulation and/or combustible air-moisture-vapor barriers in wall systems—special detailing and letters of engineering equivalency may be required.)

Example 1−masonry cavity wall with 2-in. rigid XPS insulation
A typical 406-mm (16-in.) masonry cavity wall with a 100-mm (4-in.) masonry veneer, 70-mm (2 ¾-in.) air space, 50-mm (2-in.) rigid insulation, an air/moisture/vapor (AMV) barrier, and 200-mm (8-in.) lightweight CMU back-up is shown in Figure 7. Using prescriptive Method B, the ASHRAE table requires an assembly U-factor of U-0.090 or R-11.11 for Zone 5. The resulting R-value of 13.88 exceeds the required minimum of R-11.11 by 25 percent.

If Method A was used, the ASHRAE table requires R-11.4 ci, which, for example, would equal about 64 mm (2 ½ in.) of extruded polystyrene (XPS) insulation or by rounding up to a more common size 76 mm (3 in.). As noted, Method B is not as efficient as Method A. By using only 50-mm (2-in.) XPS (R-10) continuous insulation and the component material R-values, the cumulative assembly (R-13.88) exceeds the required minimum of R-11.11.

Example 2−masonry cavity wall with 3-in. rigid XPS insulation
A typical 406-mm (16-in.) masonry cavity wall with a 100-mm (4-in.) masonry veneer, 45-mm (1 ¾-in.) air space, 76-mm (3-in.) XPS rigid insulation, an air/moisture/vapor (AMV) barrier, and 200-mm (8-in.) lightweight CMU backup is shown in Figure 8. The wall assembly complies with both prescriptive Methods A and B, and exceeds the assembly minimum by 70 percent—this means it is suitable for ‘high-performance’ and LEED projects. The overall wall configuration remains at 406 mm, and the resulting air space is 45 mm.

Example 3−masonry veneer with 6-in. stud backup and 2-in. high-R insulation
Masonry veneer with steel-stud backup is more complex than masonry veneer with CMU backup because of higher minimum R-value requirements due to energy loss through steel studs, cavity width limitations, and dewpoint locations. The maximum cavity (distance from face of steel stud to back of brick) is 114 mm (4 ½ in.) in accordance to MSJC’s Building Code Requirements and Specifications for Masonry Structures, Chapter 12.

This is prescriptive design only and engineering calculations are common for cavities exceeding 114 mm, which require more insulation to meet energy requirements. Also, many manufacturers now make stronger masonry ties, fasteners, and anchors that can easily span wider cavities. The wall configuration in Figure 9 yields a total R-value of 16.04 (U=0.063) which is only three percent over the 2012 IBC/IECC/ASHRAE 2010 requirements, and does not meet 2015 IBC/IECC/ASHRAE 2013 R-value of R-18.18.

It is important to note this wall configuration uses ‘high-R’ (2 1/8-in.) XPS insulation (R-5.6 per inch), which is more expensive than 50-mm (2-in.) XPS (R-5 per inch). This example does not factor in any additional stud backup energy loss, which will vary with stud spacing and wall configurations.

Example 4−masonry veneer with 6-in. stud backup and 3-in. high-R insulation
Figure 10 demonstrates use of 76-mm (3-in.) ‘high-R’ XPS insulation. The cavity has been increased to 127 mm (5 in.), which will require engineered anchors. The resulting 35-mm (1 3/8-in.) air space is well below the 50-mm (2-in.) industry standard, and less than the 38-mm (1 ½-in.) acceptable air space.

One option is to add a 9.5-mm (3/8-in.) continuous drainage mat to assist at preventing mortar bridging, which can lead to efflorescence, water penetration, restricted water drainage and reduced air flow. The net air space of 25 mm (1 in.) would also meet MSJC’s code minimum. Another option would be to simply increase the overall cavity to 140 mm (5 ½ in.), which would result in a 48-mm (1 7/8-in.) air space.

The wall configuration in Figure 10 yields a total R-value of 22.82 (U=0.044), which exceeds the 2012 IBC/IECC/ASHRAE 2010 requirement of R-15.63 by 48 percent, and the 2015 IBC/IECC/ASHRAE 2013 R-value of R-18.18 by 25 percent.

Example 5−masonry veneer with 6-in. stud backup, 2-in. XPS insulation, and R-8 stud space insulation
Another option for insulating steel stud backup walls is to combine rigid cavity insulation with insulation between the studs. In this example, the 114-mm (4 ½-in.) maximum cavity is maintained the air space is an acceptable 48 mm (1 7/8 in.). Caution is advised as a dewpoint analysis is required to reduce the potential for condensation within the stud space. Generally, the maximum stud space insulation should not exceed R-8 in Climate Zone 5 conditions. Most designers avoid additional insulation in the stud space.

The wall configuration in Figure 11 yields a total R-value of 22.04 (U=0.046), which exceeds the 2012 IBC/IECC/ASHRAE 2010 requirement of R-15.63 by 41 percent, and the 2015 IBC/IECC/ASHRAE 2013 R-value of R-18.18 by 21 percent.

The dewpoint theory predicts condensation in a system at any point where the actual and dewpoint temperature lines cross. Figure 12 represents the dewpoint analysis for the ‘Example 5’ stud wall configuration. For this particular assembly, if the rigid insulation was changed to R-10 and the stud space insulation was R-13 as shown for Method A Table 5.5-6 of ASHRAE 90.1 2013, the dewpoint would fall in the stud wall space (Figure 13). This is not recommended.

It is also important to carefully review air/moisture/vapor barrier properties and location within the various wall systems for the building’s climate zone.

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Which bridge to take: Structural or thermal?
Continuous insulation is defined in ANSI/ASHRAE/IES 90.1-2013 (I-P Edition) Section 3.2 (“Insulation”) as:

Insulation that is uncompressed and continuous across all structural members without thermal bridges, other than fasteners and service openings. It is installed on the interior or exterior or is integral to any opaque surface of the building envelope. [emphasis added]

Therefore, the code does not require a reduction in R-value calculation for masonry ties, fasteners, or anchors. This is further confirmed in the ASHRAE report, “Thermal Performance of Building Envelope Details for Mid-and High-rise Buildings” (5085243.01 MH 1365-RP July 6, 2011). Brick ties are considered a clear field anomaly, and are not considered practical to take into account on an individual basis for whole building calculation (Figure 14). However, companies now manufacture various masonry ties that provide additional resistance to thermal breaks (Figure 15).

Today, masonry ties must not only effectively hold the veneer in place (especially with wider cavities), but they must also be as energy-efficient as possible while helping to create an airtight seal at the penetration point of the air barrier. New anchors are being developed with ‘thermal breaks’ built into the anchor itself to further reduce any thermal bridges, with 2D and 3D modeling showing that a properly designed thermally broken anchor can improve energy performance of a wall assembly.

‘Gasketed’ veneer anchors are critical to the success of any air barrier system, as those penetrations can not only allow potential moisture infiltration, but also be a thermal weak point that can break the continuity of the building envelope. Obviously, the study of these new anchors primarily is involved with metal stud construction where thermal bridging issues have been most prominent.

Other construction assemblies and connections require closer consideration and evaluation. Examples of these linear anomalies are shelf angles and slab edges. Typical masonry shelf angles can be suspended away from the structure by clip angles or pre-manufactured supports—this allows the rigid insulation to continue behind the shelf angle, reducing thermal loss. Of course, there are still clip angles at periodic spacing (e.g. 1220 mm [48 in.] on center [oc]) as determined by the structural engineer of record that must be considered. These fall into the classification of point anomalies as shown in Figure 16.

It is essential the architect and engineer determine which bridge to take. The structural bridge would favor the shelf angle tight to the structure to reduce the cantilevered loads and save costs. The thermal bridge would use the clip angles to reduce energy costs. How does one decide? Simply add up the costs and compare (Figure 17).

If the added structural cost to add clip angles to the relieving angles for a project is $100,000 and the owner will save $400 month in energy consumption, it will take 20 years to ‘break even.’ While this is just a hypothetical example, it is important to carefully analyze the cost benefits.

It is also important to analyze the entire building envelope, including the percentage of fenestration. If the building has a significant area of glass with R-values of R-3 to R-5, the cost to increase the R-value for a small percentage of the opaque walls at shelf angle may be unwarranted. Once again, evaluations are required.

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Conclusion
There are various masonry wall assemblies to achieve energy-efficient designs that comply with, and exceed, national energy requirements, LEED, and other high-performance standards. It is important to remember that ‘over-insulating’ opaque walls is not always cost-effective. There is a point where thicker insulation with a higher R-value just does not yield a return on investment (ROI). While buildings may consume a great deal of energy, a greater amount is used with electric lights, equipment, HVAC, and plug loads than through the loss of energy with the building envelope.

Traditional masonry walls can be designed using current technology for insulated-ventilated façades that are practical, energy-efficient, and cost-effective. These walls can also be transformed into modern, contemporary buildings.

Notes
1 The term “residential” does not apply to basic single family homes. As its name suggests, ASHRAE 90.1 provides energy standards for buildings “except low-rise residential buildings” based on the following definition: low-rise residential buildings: single family houses, multi-family structures of fewer above grade, manufactured houses (mobile homes), and manufactured houses (modular homes). Energy requirements for these buildings are indicated in the International Residential Code (IRC). (back to top)

Richard Filloramo is area director of market development and technical services for the International Masonry Institute (IMI) New England Region’s Connecticut/Rhode Island Office. He holds a bachelor’s of science in architecture from Ohio State University and an associate’s degree in construction technology from Wentworth Institute of Technology. Filloramo has more than 40 years of experience in the masonry industry, and has been involved with the design, construction, or inspection of more than 5000 projects. He served as the national IMI liaison for building codes and standards and is a member of the Masonry Standards Joint Committee (MSJC)—the code-writing body responsible for the Masonry 530 Code. Filloramo can be reached at rfilloramo@imiweb.org.

Chris Bupp is director of architectural services for Hohmann & Barnard, and has been involved in the construction industry for nearly 30 years with the building envelope as his primary area of expertise. At H&B, he works with architects, structural engineers, and building envelope consultants as an educational resource and as a national speaker and writer on the subject of masonry wall design. Bupp also serves on two committees at the Air Barrier Association of America (ABAA). He can be reached at chrisb@h-b.com.

Energy Efficiency and Building with Wood: Six Building Lifecycle Steps

Buildings have an impact on people and the environment throughout their entire lifecycle, starting with extracting resources from the earth to putting them back in the earth, or burning them, at the end of their lives. To evaluate the effect of buildings in this regard, everything from the energy they consume, the waste they generate, and the carbon dioxide (CO₂) they emit must be considered throughout the six major cycles below.

The combination of wood and the Passive House standard is a common-sense approach that can have a very positive lifecycle impact on the environment. In fact, according to a report from the U.S. Forest Service, wood in building products yields fewer greenhouse gases (GHG) than other common materials.*

1. Resource extraction
Everything in buildings comes from natural resources, some of which grow relatively quickly above the ground (e.g. wood), while others take millions of years to form below the ground (e.g. materials derived from fossil fuels). Taking a look at wood, the amount of heat, water, and pollution generated compared to extracting iron to produce steel, or extracting limestone to produce cement is significantly lower.**

The lifecycle of wood has a smaller impact. For example, the sun hits the tree, and the tree grows. It can be cut down with light machinery and a new tree is planted. It absorbs carbon, provides oxygen, and can be used in the future. In this context, it means a more sustainable production, compared to making concrete or steel, where digging for oil, coal, or natural gas and then burning it is a prerequisite to extracting the raw materials from the earth.

2. Manufacturing
The real ‘weight’ of a material—including resources, water, and energy used at the entry point of a manufacturing facility—compared to the material that comes out at the other end is referred to as the ‘ecological backpack.’ This measures the environmental impact of manufacturing products. Common sense suggests it requires less resources and energy to manufacture wood products compared to concrete and steel. Heavy timber and mass timber products can meet the same structural and fire requirements that also govern concrete and steel.

3. Off-site and onsite production
In many cases, the process of constructing buildings is antiquated, relying on manual and labor-intensive onsite processes. Other fields, such as manufacturing automobiles, have advanced considerably using automation and an industrialized system approach to designing and building, where the energy efficiency, in miles per gallon, can be guaranteed and the assembly occurs in a modern factory. Modern wood prefabrication processes can offer new opportunities and better working conditions. In this respect, building with wood can offer fast and efficient options for construction.

4. Operation
The natural resources needed to produce and deliver the energy consumed to heat and cool buildings for lighting, appliances, and water is the highest of all six lifecycle steps. While more efficient lighting and appliances can be specified, the only way to reduce long-term heating and cooling loads is to improve the building envelope. Airtightness is the most important element that has made the Passive House standard succeed. It can easily be achieved using modern wood carpentry, as discussed in this article.

5. Demolition
At the end of a building’s lifecycle, products are usually disposed of in landfills. Using a system approach to construction, buildings can be designed so they can be disassembled and separated for recycling. Design optimization, use of recovered wood, and specifying jobsite waste to be separated and taken to a local recovery center are all ways to reduce, reuse, and recycle.

6. Recycling
Wood from buildings can be recovered for use in other buildings or be employed to create furniture or other products. Even at the end of their second or third ‘life,’ wood products can be burned to generate energy or decompose naturally in the earth.

*See USDA Forest Service’s “Science Supporting the Economic and Environmental Benefits of Using Wood and Wood products in Green Building Construction.”
** For more, see the International Journal of Life Cycle Assessment article, “Wooden Building Products in Comparative LCA: A Literature Review,” by Frank Werner and Klaus Richter. Visit www.vhn.org/pdf/LCA-Wood-algemeen.pdf.

To read the full article, click here.

Energy Efficiency and Building with Wood

Photo © Norman A. Müller

Photo © Norman A. Müller

by Nabih Tahan, AIA

In creating energy-efficient buildings, one of the most important goals is to accurately predict during the design stage how a structure will perform when occupied—not only the natural resources used to produce it, but also the ongoing energy consumed for its regular operation. New opportunities combining modern carpentry techniques and the Passive House standard help achieve these goals.

There are three main ways to make a building energy-efficient—using less energy, generating more energy with renewable resources, or taking a combined approach of the two. In this author’s opinion, doing both is the best option. However, it is first important to eliminate heat losses due to design strategies and construction techniques.

In winter, heat in buildings is often needlessly lost due to conditioned air escaping through cracks in the envelope. To replace this heat, heaters are used. Eliminating air leakage and heat loss in buildings by making them airtight is the most important factor for making buildings energy-efficient.

New wood building systems have been developed to offer greater airtightness to minimize energy consumption. The building industry should focus on combining the two aspects of using renewable building materials and energy efficiency to achieve comfortable buildings, while optimizing indoor air quality (IAQ) and reversing the negative effect of climate change. (See “The Six Lifecycle Steps” to understand the advantages of combining wood and energy efficiency when specifying a building system.)

New building materials created through advanced versions of engineered wood are changing non-residential construction. With the right techniques, they can bring about improved energy effi ciency. Photo courtesy Nabih Tahan

New building materials created through advanced versions of engineered wood are changing  non-residential construction. With the right techniques, they can bring about improved energy efficiency. Photo courtesy Nabih Tahan

Europe is far ahead of North America when it comes to monitoring and reporting energy consumption of buildings and homes. This image comes from Ireland’s Building Energy Rating (BER) program for residences. Image courtesy Sustainable Energy Authority of Ireland

Europe is far ahead of North  America when it comes to  monitoring and reporting energy consumption of buildings and homes. This image comes from Ireland’s Building Energy Rating (BER) program for residences. Image courtesy Sustainable Energy Authority of Ireland

Using and measuring energy
It is not enough to design buildings using energy efficiency strategies—they must also be constructed accordingly and then meet the energy consumption goals of the design during operation. This is similar to a car manufacturer designing and producing a vehicle with a specific fuel economy, and then having the car actually meet that target. Everyone is familiar with comparing cars in terms of ‘miles per gallon,’ and now a similar unit of measurement for buildings is needed. At some point, this metric for energy consumption of a building or apartment might even be included in the Multiple Listing Service (MLS).

The European Union (EU) requires every building have an Energy Performance Certificate listing the energy consumption of space heating and cooling, water heating, lighting, and appliances. The certificate must be available to buyers and tenants when a building is constructed, sold, or leased. In Europe, the unit of measurement used for the certificate is kWh/m2/year.

In the United States, energy consumption in buildings is compared to the local energy code requirements in relative numbers as opposed to a consumption rate. Buildings are described as being a certain percentage better than the prevailing code, rather than having their actual consumption cited. As new energy code updates take effect, a similar unit of measurement comparable to the Energy Performance Certificate will be established. In the meantime, the Passive House standard is a good tool to measure and compare how much energy buildings are consuming.

For new-generation wood projects, walls are simply stood up and windows, siding, and trim are installed. Photo courtesy Nabih Tahan

For new-generation wood projects, walls are simply stood up and windows, siding, and trim are installed. Photo courtesy Nabih Tahan

Preparation for blower door test for LCT ONE—a Passive House-certifi ed, eight-story wood offi ce building in Austria. Photo courtesy Cree GmbH

Preparation for blower door test for LCT ONE—a
Passive House-certified,eight-story wood office
building in Austria. Photo courtesy Cree GmbH

 

 

 

 

 

 

 

 

 

 

Passive House and net-zero energy design
Passive House is a European-developed standard that has recently found its way to North America. The original German name ‘PassivHaus’ refers to both commercial and residential buildings. Rapidly gaining popularity in North America, the standard demands high-performing building envelope assemblies and airtightness.1

Passive House calculates energy consumption (in kWh/sf/year), and includes energy-use from space heating, cooling, and ventilation systems, along with water heating, lighting, and appliances. Under the standard, the maximum energy allowed for heating and cooling is 1.4 kWh/sf/year. The standard has become successful because it has proven it can accurately predict, during the design stages, the building’s eventual energy consumption. (This is comparable to a car company claiming a car will get 30 mpg and proving to be correct.) Predicting the energy consumption in the design stages is done with the Passive House Planning Package—an energy modeling tool.

The Passive House standard is a whole building strategy that harmonizes all aspects of a structure beginning with data on local weather and solar orientation and continuing with the design, layout, foundation, framing, and insulation systems to reduce, or even eliminate, thermal bridging. It also optimizes specification of the openings (i.e. doors, windows, and curtain walls), heating, cooling, and ventilation systems, along with lighting and appliances.

Specific to thermal properties, it is important to incorporate building materials that have low thermal conductivities, and design details that minimize thermal bridging. By nature, wood is ideal for this, made up of thousands of open cells that make it difficult to conduct heat. In fact, the thermal properties of wood products are 400 times better than steel and 10 times better than concrete.2

Most importantly, Passive House has a specific requirement for airtightness, which is where the biggest connection to modern wood carpentry is made. Airtightness is measured with a blower door test.3 Air is either pumped into or sucked out of a building to see how much air is leaked, in both pressurized and depressurized states. This is similar to fixing a leak in a bicycle inner tube. Air is pumped into the tube and placed in water and the leaks are found by following the bubbles. For buildings, smoke or other instruments are used to find leaks during a blower door test. If the test is performed before the building envelope is covered up, the leaks can be sealed to make the building airtight.

Lighting and all appliances (including ovens, cooktops, refrigerators, toasters, and computers), generate some heat. Instead of allowing this heat to escape through a leaky building envelope, it is trapped inside a tight building envelope. A mechanical ventilator, with a heat recovery component, brings in fresh air into the living spaces and removes the same amount of stale air from kitchens and bathrooms.

The heat in the outgoing stale air is transferred to the incoming fresh air inside the ventilator. This recycling (or ‘U-turn’) of ‘free’ heat’ that comes out of everyday appliances and lighting can dramatically reduce a building’s energy consumption. Future energy codes in North America will also be targeting a net-zero energy standard. A net-zero energy building is hooked up to the grid and draws electricity and natural gas from the grid. The building also has a source for generating renewable energy such as solar or wind energy. During a one-year period, the amount of energy a building draws from the grid has to equal the energy it generates from renewable resources. The easiest way to meet the net-zero energy standard is to consume less energy, which is where the strategy of Passive House, in combination with modern carpentry, becomes valuable.

To combine this strategy with the choice of materials and construction methods, use of modern engineered wood products—stable, cut accurately with computerized equipment, and assembled under a controlled environment—results in airtight buildings that are automatically energy-efficient.

Prefabrication and modular wood construction is helping building designers achieve this while increasing the speed of construction and reducing project cost. Energy-efficient design is also becoming more important in North America, as the U.S. Department of Environment (DOE) has a goal of all new commercial buildings being ‘net zero’ by 2025.

This photo shows framing lumber cut with computer numerical control (CNC) machinery. Photo courtesy Nabih Tahan

This photo shows framing lumber cut with computer numerical control (CNC) machinery. Photo courtesy Nabih Tahan

Wall elements are produced on tables. Photos courtesy Cree GmbH

Wall elements are produced on tables. Photos courtesy Cree GmbH

 

 

 

 

 

 

 

 

Wood technology
When talking about wood construction, the reference points are traditionally stick-frame, or light-frame residential construction. Modern wood construction falls under the category of heavy timber, using large-dimensioned posts and beams. A new category of mass timber includes cross-laminated timber (CLT)—sometimes referred to as ‘plywood on steroids.’4

The post-and-beam method of wood construction was prevalent in many cities at the beginning of the last century, before the industrial revolution introduced concrete and steel. Now, wood products are beginning to increase again in popularity due to awareness over some of the negative environmental effect of products extracted and manufactured with intensive use of fossil fuels. Of course, this is not to say one product type is always better than another—each material has special properties and they should be combined to make hybrid buildings.

Modern timber products for structural framing are referred to as engineered lumber. These members use smaller pieces of wood, eliminating the need to harvest large trees. The ends of these smaller pieces are finger-jointed and glued to make longer pieces. Several long pieces are laminated together to make large glued-laminated (glulam) post and beams. This lumber is stable and will not shrink or twist because it is dry, which is a great advantage for airtightness, performing much better than traditional stick frame wood with higher moisture content.

For fire safety, heavy timber is allowed under the 2012 International Building Code (IBC). Wood burns approximately 38 mm (1.5 in.) per hour. Therefore, the fire regulations allow the size of structural members to be increased by 38 mm per hour for each exposed member. If a member requires two-hour fire protection, 76 mm (3 in.) are added to the size required structurally. Light-frame construction is similar to kindling for a fire. Heavy timber construction cannot be ignited without kindling; like throwing a large log into a fire, heavy timber members will char, protecting their structural integrity and strength.5

The modern process of carpentry is based on digital, computerized information. The carpentry company receives the computer-aided design (CAD) drawings from the architect. They transfer the drawings to 3D-CAD/computer-aided manufacturing (CAM) program where the wood frame can be looked at in 3D and the structure can be optimized. This is called optimal value-engineered, or ‘smart,’ framing.

Every piece of wood is placed in an exact location and has a purpose. Unnecessary framing members are eliminated and replaced with insulation to optimize energy performance.

The material is then fed to a wood-cutting machine that uses the computer numerical control (CNC) data to precisely cut all the elements. The engineered lumber is stable and is cut precisely and eliminates waste since the members can be 12.1 to 18.2 m (40 to 60 ft) long. The individual pieces are assembled together in a facility, working on tables and prefabricated into wall, floor, and roof elements. These components can be quickly erected onsite in an airtight manner, ensuring energy-efficient construction.

Instead of asking carpenters to measure, cut, and assemble walls and floors onsite, employing labor-intensive processes, the carpenters are moved in a controlled environment, where they are given the drawings and pieces for each component to be assembled, making use of overhead cranes and forklifts to protect their bodies.

The advantage of this process is it optimizes the construction, guarantees stable material, and accurately cut pieces and assembled components that fit together tightly. Specifically designed tapes and gaskets are used at the intersection of panels to prevent air leakage. As proof of performance, the building can be tested for airtightness by a third party by administering a blower door test to meet the ≤ 0.6 air changes per hour @ 50 Pascal pressure—one of the main requirements of the Passive House standard.6

This wall element was craned in place. These types of components can be completed onsite in an airtight manner.

This wall element was craned in place. These types of components can be completed onsite in an airtight manner.

This is an example of precision cutting using CNC machinery. Photo courtesy Nabih Tahan

This is an example of precision cutting using CNC machinery. Photo courtesy Nabih Tahan

 

 

 

 

 

 

 

 

Conclusion
Combining modern wood technology and Passive House strategies helps save resources and achieves energy efficiency in buildings. The fundamentals of modern carpentry are based on:

  • optimizing the timber structure;
  • uses stable engineered lumber;
  • cutting the material accurately using industrial machinery;
  • prefabricating components under a controlled environment; and
  • assembling them quickly onsite to be cost-competitive, while automatically meeting airtightness requirements.

Using this construction process and modern carpentry skills, the building envelope’s thermal performance and airtightness can be predicted during the design stages. To prove the performance, the envelope is tested for airtightness with a blower door test after assembly. Similarly, the energy performance of a building can be predicted using the Passive House standard during the design stages—through the thousands of certified buildings in Europe, the actual energy consumption during occupancy has been shown to match the predicted values.

Overall, the use of new modern wood technologies can have a positive effect on construction industry from job creation to reduced environmental impact.

The design team, including architects and engineers, can collaborate to ensure wood-based building envelopes can meet these high-performance standards. In collaboration with the Passive House consultant, the design team can determine which layer in the wall/floor/roof assemblies prevent air leakage and include details on how to seal intersections and penetrations.7 They can model heat transfer effect in building components to eliminate or reduce thermal bridging and specify available products for taping and sealing joints proven to be durable and long-lasting.8

Notes
1 There have been dozens of certified projects in North America, and the numbers are growing fast. There are two competing U.S. organizations, and both of them have databases and listings for these projects. The North American Passive House Network (NAPHN)—www.naphnetwork.org—is directly affiliated with the Passive House Institute (PHI) in Germany, while the Passive House Institute US (PHIUS)—phius.org—was founded by someone who used to work with PHI, before branching off.
2 For more information, see Naturally Wood’s “Green Building with Wood–Module 3” at www.naturallywood.com/sites/default/files/Module-3-Energy-Conservation.pdf.
3 The Passive House Institute requires the test to meet the European Standard EN 13829, Thermal performance of buildings: Determination of air permeability of buildings, fan pressurization method. In the United States, ASTM E1927, Standard Guide for Conducting Subjective Pavement Ride Quality Ratings, and ASTM E779, Standard Test Method for Determining Air Leakage Rate by Fan Pressurization, would be used with Resnet Protocol Chapter 8, “Enclosure and Air Distribution Leakage Testing.”
4 The limitations of these types of wood assemblies are the current building codes or special approval by a jurisdiction for alternative means of design and construction. Obviously, it is not a one-for-one switch between wood and concrete—the architect and engineers have to run calculations for both materials to ensure the design meets the structural, seismic, acoustic, and thermal requirements. At the moment, the building codes limit wood buildings to 75 ft (i.e. 23 m). The wood industry is in the process of testing new wood products such as CLT for fire and seismic performance. This author’s company is in the process of negotiating a partnership/joint venture agreement to participate in an Expression of Interest for a 16 to 18-story student residence building utilizing advanced wood-based building system, physically demonstrating the applicability of wood in the tall building market.
5 For more on wood and fire resistance, see “Design of Fire-resistive Exposed Wood Members,” by Bradford Douglas, PE, and Jason Smart, PE, which appeared in the July 2014 issue of The Construction Specifier.
6 Visit www.passiv.de/en/02_informations/02_passive-house-requirements/02_passive-house-requirements.htm for more information.
7 This is a consultant that collaborates with the architect, and structural, mechanical, and electrical engineers. During the design stages, the passive house consultant begins the energy modeling in the Passive House Planning Package (PHPP) tool to determine the heating, cooling, and electrical loads. The PH consultant then submits the calculation to either PHI or PHIUS for pre-certification. The MEP engineers use these calculations to design the system, and the architect and structural engineers design the details to eliminate or reduce thermal bridging.
8 For more, see this author’s previous article, “LCT ONE–A Case Study of an Eight-story Wood Office Building,” in the March 2014 issue of The Construction Specifier.

Nabih Tahan, AIA, is an international architect, Passive House consultant, and CEO of Cree Buildings Inc. For more than 30 years, he has honed his knowledge in architecture, energy efficiency, and sustainable timber-based construction methods through work in Austria, Ireland, and the United States. Currently, Tahan is guiding Cree Buildings to establish a systems approach to design and construction, combining wood and energy efficiency strategies to build single-family and multi-family residential projects, along with office buildings. He can be contacted at nabih.tahan@creebuildings.com.

Stay in Control: Specifying building automation systems for cost savings

The Sheraton Phoenix Downtown Hotel uses a BACnet (data communication protocol for building automation and control networks) compatible building automation system (BAS) for energy savings and occupant comfort. All images courtesy Alerton

The Sheraton Phoenix Downtown Hotel uses a BACnet (data communication protocol for building automation and control networks) compatible building automation system (BAS) for energy savings and occupant comfort. All images courtesy Alerton

by Kevin Callahan

In the same way today’s mobile phones have capabilities far beyond traditional telephones, modern building automation systems (BAS) have added many benefits transcending their original roots in heating and cooling control.

Today’s BAS help facility professionals obtain greater efficiencies from numerous building systems, including:

  • lighting;
  • security/access control;
  • fire and life safety;
  • elevators and escalators;
  • irrigation; and
  • HVAC.

An appropriately equipped BAS can also meet specialized needs such as emergency and critical systems monitoring in hospitals, and tenant billing for leased spaces in office buildings.

With rising energy costs, an increasing number of building owners and operators are including BAS in new buildings, as well as in retrofits. More than half of U.S. buildings larger than 9290 m2 (100,000 sf) have a BAS installed.1 The market is forecast to grow between seven and nine percent from 2014 through 2017, for a net growth of more than 40 percent above the 2012 level, according to researchers at IHS Technology. A key driver of this “/>growth is a projected eight percent annual increase in retail electricity prices through 2020.2

Building automation systems software with an intuitive, graphical interface is simple to use and helps reduce or eliminate the need to train staff on operating the system.

Building automation systems software with an intuitive, graphical interface is simple to use and helps reduce or eliminate the need to train staff on operating the system.

Vendors now offer BAS wall units with the sophistication and elegance of smartphones.

Vendors now offer BAS wall units with the sophistication and elegance of smartphones.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BAS benefits
Automation can reduce a building’s total energy consumption between five and 15 percent annually because of more efficient control of various building systems. Savings can surpass 30 percent annually in older or poorly maintained buildings. Additionally, a BAS can help reduce building maintenance costs by alerting facility managers when equipment is operating outside of specifications and therefore might be at risk of failure.3

The facilities management and planning department at Boston University outlines these and other BAS benefits as follows:

  • control and diagnose what is going on in buildings;
  • create a graphic representation of building settings;
  • see and fix programmatic problems quickly;
  • generate reports usable by management for tracking energy consumption and the operational status;
  • schedule and control temperature settings for increased energy savings; and
  • collect and store data on energy consumption over long periods.4

Project examples
From commercial offices and government buildings, to schools and hospitals, energy saving benefits can be achieved in virtually every type of project.

Commercial offices
Seattle’s Columbia Center is the tallest building in the Pacific Northwest, with 76 stories and 142,900 m2 (1,538,000 sf) of total floor area. A BAS integrates all the building’s HVAC systems—including 2200 heat pumps, ventilation and exhaust fans, boilers, heat exchangers, cooling towers, and circulation pumps.

The building is one of the city’s largest electricity-consumers, using approximately 111,600,000 megajoules (31,000 megawatt hours) annually. However, with an energy-efficient BAS, it consumes only about 13 percent more electricity than the next highest building electricity consumer in the city, despite having 50 percent more floor area.

Government buildings
In 2009, the state of California opened a new central utility plant in Sacramento to heat and cool many office buildings throughout the city. The 7246-m2 (78,000-sf) facility supplies chilled water and steam to 23 buildings that total 510,967 m2 (5,500,000 sf) of space. One BAS monitors and controls the central utility plant, while another BAS serves the 23 buildings. The BAS for the chiller plant enables it to operate at about half the energy use of a traditional chiller plant.

K–12 schools
At Irvington High School in Fremont, California, the local school district installed a BAS as part of a set of energy-saving actions that reduced the school’s energy consumption by approximately one-third, which equates to annual savings of about $10,000. Much of the savings result from data provided by the BAS, which allows the district to shed energy loads under a peak pricing program offered by Pacific Gas and Electric (PG&E).

Universities
Eastern Connecticut State University in Willimantic installed a BAS in the Windham Street Apartments—a 30-year old, nine-story residence hall housing 224 students. The BAS reduced the building’s annual electricity consumption by 234,000 megajoules (65 megawatt hours), for a 12 percent energy cost savings. The university achieved these savings despite also adding cooling to the building, when previously it only had heating.

Hospitals
As part of a facility expansion and upgrade project, New York University Medical Center in Manhattan retrofitted outdated building controls in 13 buildings totaling 278,710 m2 (3,000,000 sf). The new BAS enables staff to manage the campus and outlying facilities through a single system, for better energy efficiency. Additionally, trend logs generated by the system illustrate how closely actual room temperatures match the set point, which allow staff to closely control the environment for patient comfort, health, and safety.

This wall unit includes subtle light-emitting diodes (LEDs) along its bottom so users can see at a glance when the HVAC system is in heating or cooling mode.

This wall unit includes subtle light-emitting diodes (LEDs) along its bottom so users can see at a glance when the HVAC system is in heating or cooling mode.

A properly equipped building automation system allows higher education facility managers to centrally monitor and control multiple buildings across campus, including at campuses in other cities.

A properly equipped building automation system allows higher education facility managers to centrally monitor and control multiple buildings across campus, including at campuses in other cities.

 

 

 

 

 

 

 

 

 

Maximizing BAS benefits
To receive the most benefits from implementing a BAS, it is important to focus on analytics and building commissioning.

Analytics for high-performance building operations
A BAS is a powerful tool for gathering data needed to make informed decisions on energy management. To maximize its cost-saving potential, one must pay attention to the data the system is generating and to use it to make strategic energy usage choices—this is the concept of building analytics. In short, a BAS is not a tool to install then simply turn the heating, cooling, and lights on and off according to a set schedule.

Analytics is about ensuring a building’s managers have enough of the right data being collected for analysis. It is important to use analytics to ensure any BAS programs created to reduce energy—or any other objective—are actually accomplishing what was intended. An appropriately equipped BAS allows the facility staff to collect and store data so there is history to compare it to.

For example, analytics can help the facility managers ensure they are not heating and cooling the same spaces at the same time, as well as confirm lights are on for a purpose, rather than solely for convenience. Analytics provide a way to determine whether energy is being wasted, and where.

A BAS delivery agent (i.e. manufacturer, dealer, or consultant) can be a valuable resource for determining what analytics are needed to meet the building owner or operator’s specific goals.

Building commissioning
A sometimes overlooked benefit of BAS is the system can be used to simplify the commissioning process, for both new construction and building retrofits. Some BAS include programs to verify HVAC and other building systems are performing according to the design intent. The wall sensors of an advanced BAS enable technicians to access the system throughout the building to conduct tests and verify environmental conditions, without carrying separate diagnostic tools—the result is faster and more accurate performance verification. Proper building commissioning is crucial to achieve efficient building operations.

“The operating costs of a commissioned building range from eight to 20 percent below that of a non-commissioned building,” reports the U.S. Environmental Protection Agency’s (EPA’s) Building Commissioning Guidelines. Additionally, it is noted commissioning costs typically range from only 0.5 to 1.5 percent of construction costs, and reduce operating costs throughout the building’s life.5

For initial commissioning, the building systems as a whole need to be commissioned at the time of construction to ensure they are operating as designed and their integration with the BAS is correct. This helps ensure the building is operated appropriately to satisfy its occupants’ needs. As a basic example, in an office building the HVAC and lighting would need to be commissioned for controlling the indoor environment while the building is in use during standard working hours, whereas in a warehouse the utility needs would be different because the building likely is not in use at all times.

An even more critical action than initial commissioning is the periodic re-commissioning of a building to ensure the systems are still serving the occupants’ requirements. Additionally, because systems can degrade over time, it is important to tune them up for optimal performance.

The Russellville School District in Arkansas uses its building automation system to monitor food and beverage freezers and coolers in its facilities.

The Russellville School District in Arkansas uses its building automation system to monitor food and beverage freezers and coolers in its facilities.

The BAS for this Sacramento central plant enables it to operate at about half the energy use of a traditional chiller plant.

The BAS for this Sacramento central plant
enables it to operate at about half the
energy use of a traditional chiller plant.

 

 

 

 

 

 

 

 

 

Specifying a BAS
Design professionals can select from numerous BAS. Several important features to consider when choosing the system include:

  • degree of interoperability of the control module;
  • software’s ease of use;
  • security measures; and
  • usability and design style of the wall sensors.

Control module
The control module is the central processing unit of a BAS. Until the mid-1990s, the communication protocols these units used to interface with building equipment were proprietary to each manufacturer. As a result, various components would not work together unless using a single manufacturer’s equipment.

In 1987, the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) began to actively develop a standard protocol to enable a wide range of controls and equipment to work together (i.e. interoperable). In 1995, it published that standard—known as BACnet (data communication protocol for building automation and control networks), which has since been widely adopted by BAS and building equipment manufacturers.6

“Capabilities vital to BA [building automation] applications were built into BACnet from the beginning in order to ensure the highest possible level of interoperability in an environment possibly involving multiple vendors and multiple types of building systems,” according to a report from the Institute of Electrical and Electronics Engineers (IEEE).7

Such interoperability helps ensure a BAS can adapt to emerging technologies and evolving building occupancy needs, without having to start over.

BACnet is unparalleled in providing integration of the disparate systems within a building, including HVAC, lighting, access, irrigation, utility monitoring, and metering. For example, instead of having separate systems and building occupancy schedules for a building’s lighting and HVAC systems, BACnet allows for clean integration of both systems so the scheduling is from one source.

By analogy, a BAS using BACnet is like a symphony orchestra, wherein the control module is the conductor providing direction to the numerous different building systems (i.e. individual musicians) using a common protocol (i.e. BACnet) they all understand (i.e. movements of the baton, hand gestures, and facial expressions). Although a violin is different from a trumpet, the conductor’s common direction enables them to work together to produce beautiful music.

Some BAS control modules incorporate multiple protocols (BACnet and Tridium’s Niagara Framework) for even greater interoperability than relying on a single protocol. Other protocols, like LonTalk, are also available.

Software—ease of use
Learning a new software program often involves hours of training, and/or trial and error, both of which can mean thousands of dollars in staff time. This is especially true for specialized programs such as those included with a BAS.

However, a key differentiator among BAS software is how intuitive and simple it is to learn. Although many programs now employ a graphical interface, rather than text entry alone, ease of use varies. The most sophisticated BAS software includes simple schematics clearly identifying the equipment throughout a building, and its operating status (e.g. heating, cooling). Such programs enable even novice users to readily interpret the environmental or other monitored conditions anywhere in the building, and to adjust the appropriate building system, as needed.

Another simplifying feature introduced with BAS software this year is use of HTML5. With the latest HTML format, facility professionals can access the BAS remotely from any Internet-connected device, without the time and compatibility hassles of downloading a third-party’s software plug-in. As a result of this wide system accessibility, a technician could troubleshoot a piece of equipment from the field, or a facility manager could make necessary system adjustments when traveling away from the office.

Security measures
As large online security breaches have come to light in recent years, building professionals are increasingly asking about how to secure their Internet-facing building BAS. For the building design team, three cyber security best practices will improve the security of a building automation system against unauthorized access:

  • ensure network isolation by deploying behind a firewall or on a virtual private network (VPN);
  • use the security features built into the BAS; and
  • configure the system securely by disabling guest user accounts and using strong password protection protocols.

Since BAS are networked throughout buildings (and often to the Internet) to enable remote access by facility managers, it is crucial to isolate the automation system from other internal networks, such as financial management or credit card processing. To accomplish this, the building design team should involve the client’s information technology (IT) experts early in the BAS selection process, as this is a specialized aspect of specification writing and usually requires acquisition and installation of additional hardware dedicated to protecting the building networks from both external and internal attacks. This hardware (e.g. firewalls, VPN routers) is extremely important and needs to be state-of-the art to combat the evolving means of attacking networks.

For the BAS itself, a control module with multiple Ethernet ports is an important security feature that helps to isolate the network. Such control modules physically separate the building systems from connections to outside networks. It is also important to specify a BAS that can be configured to use signed certificates for web connections to prevent ‘man-in-the-middle’ attacks when users log into the server. Beyond network connections, another security feature built into some BAS is a system that does not automatically execute code from USB thumb drives. This helps prevent a BAS user from inadvertently introducing a virus or other malware into the BAS.

Building automation systems are installed throughout the world, including in this Turkey skyscraper.

Building automation systems are installed throughout the world, including in this Turkey skyscraper.

Securely configuring the system once it is installed is important, so it is critical to ensure the BAS has a security manual that provides information on how to best accomplish this task, and then make sure the contractor follows those guidelines. Additionally, the BAS integrator should have documented the processes and procedures they followed for designing and implementing the system, which will be a crucial reference for the building owner.

Cyber-security threats change frequently, and need constant vigilance. Anyone who touches the system should be trained at a minimum in cyber-security awareness, and ideally should be certified to securely deploy vendor systems. It is also important they are aware of the building owner’s cyber security standards and practices. Building owners should also keep in mind the BAS will require maintenance, which might include patches to the operating system, and anti-virus software updates and management.

Strong cyber-security is a three-legged stool comprising:

  • manufacturers and software vendors, who continually evaluate and improve the security of products;
  • contractors and installers, who ensure their customers’ systems are properly and securely installed; and
  • end-users, who build and maintain a culture of security within their organizations through the use of cyber security best practices.

Wall sensors
As with BAS software, a key differentiator among wall sensors is how easy they are to use—important for both facility staff and building occupants. Vendors have become increasingly sophisticated with designing wall sensors. One unit introduced in 2014 was designed according to what users are accustomed to seeing with their smartphones. For example, the unit includes easy-to-interpret icons for temperature control, and clear navigation tools to see interior and exterior temperatures, relative humidity (RH), and carbon dioxide (CO2) levels. To enable building occupants to see the HVAC operating condition from across the room, the unit has color light-emitting diode (LED) lights along its bottom to indicate either heating (red) or cooling (blue).

In terms of design styling, in commercial buildings, thermostats have often been visually ‘boxy.’ Now, manufacturers are focusing on aesthetics of these units in addition to performance. Some units are designed to be sharp and crisp with a low profile to complement modern architectural styling. Building owners and occupants have even gone so far as to say such units are ‘sexy.’ At any rate, a thermostat does not necessarily need to be a clunky box hidden around a corner, but can be a sleek addition to a room or hallway.

Conclusion
A properly equipped and configured automation system can save building owners tens of thousands of dollars or more on annual energy costs. Additionally, some facility professionals use the systems to save costs in other ways. For example, in Russellville, Arkansas, the school district officials use their BAS to monitor food and beverage freezers and coolers in schools throughout the area. The system sets off an alarm if temperatures begin to go out of range, which enables the facility staff to take prompt action and thereby avoid costly and wasteful spoilage.

To maximize the cost savings, when specifying an automation system it is important to think about each component—control module, software, and wall sensors—and consider how easy they are to use, and how flexible they are to changing technologies and building user needs.

Notes
1 For more, see “Building Automation Systems” at fpl.bizenergyadvisor.com. (back to top)
2 Visit “U.S. Building Automation Market Primed for Growth,” at technology.ihs.com. (back to top)
3 See note 1. (back to top)
4 See www.bu.edu/facilities/what-we-do/buildings/building-automation/ for more. (back to top)
5 Visit “EPA Building Commissioning Guidelines” at www.epa.gov. (back to top)
6 See “BACnet overview” at www.bacnet.org. (back to top)
7 See “Communication Systems for Building Automation and Control,” by Kastner, Neugschwandtner, Soucek, and Newman, Institute of Electrical and Electronics Engineers (IEEE), at www.researchgate.net. (back to top)

Kevin Callahan is a product marketing manager for Alerton, a Honeywell business. He has 38 years of experience in the building control technologies field, including control systems design and commissioning, facilities management, and user training. Callahan can be reached at kevin.callahan@honeywell.com.

Reducing Environmental Impact with Coatings

Images courtesy Sto Corp.

Images courtesy Sto Corp.

by Rankin Jays, MBA

A quick review of the new 2012 International Building Code (IBC) is evidence enough the environmental lobby continues to grow. Broadly speaking, the new code requires more insulation, a tighter envelope, improved ducts, better windows, and more efficient lighting. As it becomes understood the planet cannot sustain the environmental impact associated with meeting a growing energy demand, energy conservation needs to improve.

However, the code is merely the minimum acceptable standard and it still leaves choices—especially the option to make a bigger individual contribution toward energy savings. The professional community recognizes the opportunity to influence these choices on an even larger scale. Architecture 2030—a non-profit, non-partisan, and independent organization—was established in response to the climate change crisis in 2002. According to the group:

Buildings are the major source of global demand for energy and materials that produce by-product greenhouse gases (GHG). Slowing the growth rate of GHG emissions and then reversing it is the key to addressing climate change.1

The U.S. Green Building Council (USGBC) launched Leadership in Energy and Environmental Design (LEED) in 1998 as a voluntary, market-driven program to recognize environmental stewardship and social responsibility in building design, construction, operations, and maintenance. The knock-on effect was to focus the building supply chain on the industry’s products, how they were made, efficiency, and where and how they were brought to market.

Buildings are the problem and buildings are the solution. Inadequate insulation and air leakage are leading causes of energy waste in most projects, and coatings selection can play a big role in energy saving opportunities.2

Cool roofs
According to the U.S. Department of Energy (DOE), cool roofing is the fastest growing sector of the building industry, as owners and facility managers realize the immediate and long-term benefits of roofs that stay cool in the sun.3 The Oak Ridge National Library (ORNL) have explored the energy efficiency, cost-effectiveness, and sustainability of cool roofs and have developed a calculator that computes the reduction in energy consumption by substituting a cool roof for a conventional roof. Cool roofs can create a cooler interior space in buildings without air-conditioning, making occupants more comfortable, reducing carbon emissions by lowering the need for fossil-fuel generated electricity to run air-conditioners, and potentially slowing global warming by cooling the atmosphere.4

Cooler building surface temperatures reduce energy demand.

Cooler building surface temperatures reduce energy demand.

Cool (i.e. white) flat roofs have been a requirement in California since 2005, while it has been relatively easy to get building owners to adopt this it was not without incentives such as federal tax credits for approved roofing systems.5 The cool roof requirement was extended to include sloped roofs in certain Climate Zones in 2009 as part of the California’s Title 24, Building Energy Efficiency Standards. Further, roofing systems meeting LEED’s Solar Reflectance Index (SRI) criteria could qualify for LEED-New Construction (NC) v2.2 Sustainable Sites (SS) credit 7.2, Heat Island Effect–Roof.

If you are installing a new roof or reroofing an existing building, a systems approach to providing an energy-efficient roof should be taken with a cool roof considered.

Simply put, traditional dark-colored roofing materials strongly absorb sunlight, making them warm in the sun and heating the building. White or special ‘cool color’ roofs absorb less sunlight, staying cooler in the sun and transmitting less heat into the building. This reduces the need for cooling energy if the building is air-conditioned, or lowers the inside air temperature if the building is not cooled.

Steven Chu, PhD, has been talking about the benefits of white roofs since being appointed as U.S. Secretary of Energy. In 2010, he mandated all new roofs on Energy Department buildings be either white or reflective. In a statement, he noted the cooling effect white roofs have on buildings, especially air-conditioned ones, as well as their ability to drastically lower energy costs—an estimated $735 million per year, if 85 percent of all air-conditioned buildings in the country had white roofs.

“Cool roofs are one of the quickest and lowest cost ways we can reduce our global carbon emissions and begin the hard work of slowing climate change,” Chu said.

White roofs can also reduce the urban heat island effect. This is a phenomenon caused by all the dark, heat-absorbing surfaces in urban areas. A study by the Lawrence Berkeley National Laboratory’s (LBNL’s) Heat Island Group6 showed increasing the reflectivity of road and roof surfaces in urban areas with populations of more than one million would reduce global carbon dioxide (CO2) emissions by 1.2 gigatons annually—the equivalent of taking 300 million cars off the road.7

IR-reflective pigment coatings
Infrared (IR) reflective pigment technology in coatings were first used more than 30 years ago, although full commercialization has only been quite recent.8 The technology and entry costs are relatively lower now than in the past, but the manufacturing process and quality control remains specialized within the scope of only a small number of manufacturers.

Combining the IR reflective pigmentation with the performance of current polymer coatings technology can produce a long-lasting coating offering significant energy-saving potential along with numerous other benefits. The higher solar reflectance increases the coating lifecycle by reducing thermal expansion and contraction of the substrate. The cooler surface temperature reduces polymer degradation within the paint film; reduced energy demand carries the obvious economic and environmental advantages. Additionally, they also make a positive contribution toward the reduction of the urban heat island effect.

The primary purpose of IR-reflective coatings is to keep objects cooler than they would be using standard pigments. These coatings can reduce the heat penetrating the building though the roof and exterior walls, lowering the load on the air-conditioning system and thereby increasing a building’s energy efficiency. An overview of the basics behind this technology is described on the Eco Evaluator website, stating:

These thermally emissive/reflective coatings offer a range of applications such as on roofs and walls of buildings. These coatings will adhere to a variety of materials such as composite roof shingles, metal roofs, and concrete tile roofs as well as stucco, plywood, and concrete block walls. When considering thermally emissive/reflective cool coatings be sure to look for metal oxide and infra-red emissive pigments. These ingredients are necessary to block ultra violet rays and reflect infrared radiation.9

Infrared (IR) reflective coatings are gaining in popularity as exterior design incorporates more vibrant and saturated colors.

Infrared (IR) reflective coatings are gaining in popularity as exterior design incorporates more vibrant and saturated colors.

In 2005, ORNL produced a lengthy study on the efficacy of IR reflective exterior wall coatings and found they can offer up to 22 percent savings on cooling energy costs when compared to a regular architectural coating of the same color. Overall effectiveness depends on the darkness of the coating color and how exposed the surfaces are to direct sunlight.

Radiant heat barriers
Passing on the whole exterior repaint is an option—a radiant heat barrier in the attic space, primarily designed to reduce summer heat gain and decrease cooling costs, can be considered. The barrier consists of a highly reflective material that ‘bounces’ radiant heat and reduces the radiant heat transfer from the underside of the roof to the other surfaces in the attic, such as air-conditioning ducts.10

Air barriers
A report from the National Institute of Standards and Technology (NIST), “Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC Energy Use,” confirms continuous air barrier systems can reduce air leakage by up to 83 percent and energy consumption for heating and cooling by up to 40 percent.

In new construction where we may have been accustomed to seeing a building ‘wrap,’ air barriers are now commonly fluid-applied air and moisture barriers, providing a continuous and fully adhered membrane across the sheathing’s entire surface with obvious durability advantages gained from having a chemical and mechanical bond between the air barrier and the substrate.

Liquid technology also allows for faster, easier application of the air barrier and reduces the risk of improper installation as they are spray-, brush-, or roller-applied to the surface. The exception would be where mesh, fabric, or transition products are embedded and sealed within the fluid applied products.

As building codes continue to evolve with an emphasis on energy efficiency and sustainability, the value of air barriers is becoming much more apparent. In fact, research has proven air barriers actually play a larger role in energy efficiency than exterior continuous insulation.11

V

This image shows a spray application of a vapor permeable fluid applied membrane.

Niche or not?
With the exception of cool roof coatings, why have the rest of these technologies not amounted to much more than niche products? There is perhaps a large amount of skepticism following early entrants in the market that made outlandish claims of paint’s insulating qualities that were revealed as scams.

For skeptics out there, look no further than the stripes on a zebra for a lesson on reducing radiant heat. The black and white pattern on these animals can reduce the animal’s surface skin temperature by 8 C (17 F). The temperature differences over the black and white stripes result in differential air pressure, which produces minute air currents that cool the surface.

As an example of biomimicry of this natural phenomenon, the concept was commercialized by Daiwa House in Japan where the interplay of black and white on the façade reduced the summer indoor air temperature by 4.4 C (8 F).

It should be noted, cool roof and IR coatings will only have an impact where cooling costs are higher than heating costs. In higher/cooler latitudes there could be a heating cost penalty during the winter as a result of using these coatings. Following the zebra’s example they are only provided with an insulating layer of fat beneath their black stripes since the tissue below the reflective white stripes does not need it.

Conclusion
Coatings are in no way meant to replace insulation, but they can make an effective contribution in reducing the downstream environmental impact by reducing energy usage. With new coatings in the market, and more coming in every day, these products are contributing to energy savings and reducing energy dependency.

Notes
1 Visit www.architecture2030.org/2030_challenge/the_2030_challenge. (back to top)
2 Visit www.ornl.gov/sci/roofs+walls/insulation/ins_01.html, Department of Energy. (back to top)
3 For more on cool roofing, see “Rethinking Cool Roofing: Evaluating Effectiveness of White Roofs in Northern Climates” by Craig A. Tyler, AIA, CSI, CDT, LEED AP, in the November 2013 issue. (back to top)
4 Visit www1.eere.energy.gov/buildings/pdfs/cool_roof_fact_sheet.pdf. (back to top)
5 Visit www.energy.ca.gov/2008publications/CEC-999-2008-031/CEC-999-2008-031.pdf. (back to top)
6 For more, see Lawrence Berkley National Laboratory 2009, Radiative forcing and temperature response to changes in urban albedos and associated CO2 offsets. (back to top)
7 Visit inhabitat.com/having-white-roofs-would-save-the-u-s-735-million-per-year/. (back to top)
8 For more on IRCCs, see our web-exclusive article, “Reflecting on the Versatility of IRCCS,” by Lynn Walters at www.constructionspecifier.com. (back to top)
9 Visit www.ecoevaluator.com/building/energy-efficiency/heat-reflective-paints.html. (back to top)
10 Visit www.ornl.gov/sci/ees/etsd/btric/RadiantBarrier/. There is a great fact sheet from Oak Ridge National Laboratory with more information on radiant heat barriers. (back to top)
11 See, NISTIR 7238, “Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC Energy Use.” (back to top)

Rankin Jays is a product manager (coatings) for Sto Corp. He joined the company this year to oversee the coatings product line, introducing new products such as architectural coatings. Jays’ experience with coatings goes back nearly 30 years, starting as a paint maker while at Victoria University in New Zealand. He received his MBA from Massey University. Jays can be contacted by e-mail at rjays@stocorp.com.