Focus on Your Footprints
Decreasing building carbon footprints is environmentally and economically smart
By Mark Robins, Senior Editor
Carbon dioxide is everywhere today: in the air and in the news. A building's carbon footprint is the amount of CO2 it produces during its operations and activities. CO2 is a greenhouse gas that greatly contributes to negative global climate change. The level of CO2 in the atmosphere today is the highest in more than 750,000 years; the 22 warmest years ever recorded have occurred since 1980. Strong scientific consensus, a growing green movement and common sense dictate that carbon emissions must be reduced.
According to the U.S. Green Building Council, buildings account for 39 percent of CO2 emissions in the United States per year, more than any other sector. U.S. buildings alone are responsible for more CO2 emissions annually than those of any other country except China. Most of these emissions come from fossil fuel combustion to provide heating, cooling and lighting, and to power appliances and electrical equipment.
"In the 21st century, it has become evident that we need to change the way we relate to our planet if we expect our children to inherit a clean, livable planet," says Robert "Skip" Backus, CEO,Omega Institute, Rhinebeck, N.Y. In 2009, Omega Institute's award-winning Omega Center for Sustainable Living (OCSL) became the first green building in America to achieve both LEED Platinum and Living Building Challenge certification, the highest performance standards possible today.
Backus says that Omega learned when it comes to buildings, there are two aspects to a carbon footprint. "As much as 18 percent of a building's carbon footprint is created within the first year of the building's construction; the balance is 'operational,' carbon released thereafter," he says.
"Equal emphasis must be put on design, construction and operation, from materials manufacturing, to selecting materials with low-emissions factors, to transportation of materials, to reducing construction waste, to salvaging materials during demolition and using salvaged material in new construction, and lowering energy and operational costs from retrofits to green technologies."
Reducing a building's carbon footprint produces benefits. "By reducing the carbon footprint it is usually possible to reduce running costs, but there are other benefits as well," says Joanne Craft, designer at Ambius, Burnaby, British Columbia, Canada, a design and plant services company for interior business environments. "Employee engagement is often improved, rents can be higher and companies with a good record in sustainability are usually looked upon favorably by consumers, therein improving image and marketability. Also, sustainable buildings with good LEED or BREEAM scores are often more acceptable to planners and there may be incentives, or fewer disincentives to build."
BREEAM is an environmental assessment method and rating system for buildings, with 200,000 buildings with certified BREEAM assessment ratings and over a million registered for assessment since it was first launched in 1990.
Measuring carbon footprint
Before building owners can decrease their specific carbon footprint, they need to measure and then audit it. "Knowing one's carbon footprint is important for many reasons, ranging from compliance, onto corporate social responsibility and 'doing the right thing,' and then onto collecting useful management information about energy and resource use," says Kenneth Freeman, head of Ambius University and international technical director for Ambius in Harlow, Essex, United Kingdom.
An energy audit is an inspection, survey and analysis of the building's energy inputs and outputs. One component of it is requiring an Environmental Product Declaration (EPD) for the building materials used in the building's construction or renovations.
"An EPD is globally accepted as the most comprehensive way to validate a product's environmental impact, where the products are tested based on a Life Cycle Analysis (LCA), following common standards for analysis and reporting," says Kathryn Giblin, director of global marketing & technical services at Solar Gard, San Diego. "Using carbon negative building products help decrease a building's overall carbon footprint."
Most energy audits obtain a historical energy use date to establish a base year. Analysis of energy consumption within a building and within building operations will determine specific energy use and consumption patterns. These measurable patterns arise from central heating/cooling to individual office units, and energy use from laptop and desktop computers, faxes, scanners, servers, copiers, ceiling and desk fans, kitchen appliances and lighting.
An air pressurization test during building commissioning is a simple energy audit to measure carbon footprint. However, the time to consider the energy audit is in the design phase where the products, materials and construction techniques are being specified. "This is particularly true for the insulation and air sealing techniques used in the building envelope," says Doug Todd, market manager, commercial construction at Dow Building Solutions,The Dow Chemical Co., Midland, Mich. "Once the building envelope is installed, making changes and improvements can be an expensive operation. Design the building envelope properly the first time to make the downstream energy audit a success."
Carbon footprint calculators and whole-building energy-modeling tools are publicly available software tools. Some design teams and owners can convert energy savings identified in energy modeling into their approximate fossil fuel equivalents.
"In resource preservation, energy savings can be converted to tons of coal not consumed," says Steve Fronek, PE, LEED green associate and vice president of technical services at Wausau Window and Wall Systems in Wausau, Wis. "In emissions reduction, energy savings eliminate the generation of greenhouse gas and other emissions, which can be converted into:
- CO2 equivalent tonnage as reduced global warming potential,
- The amount of CO2 greenhouse gas absorbed by trees,
- The amount of smog-producing NOx that would be emitted by an auto, and
- The amount of SO2 falling as acid rain on acres of forest.
These conversions provide a context for interested, but non-technical, stakeholders."
In most cases, an independent assessor using recognized protocols would carry out the actual carbon audits. "The most widely used being the Greenhouse Gas protocol (GHG)," says Craft. "For such an assessment, the scope and boundary of the assessment has to be well defined: what is being measured and how far do you go?"
What architects can do
Should architects design buildings more effectively to reduce carbon footprints? Yes, "architects have a responsibility to produce buildings with as low an environmental impact as possible," says Freeman. "Simply ticking boxes in a rating system is not enough; a pick-and-mix approach to LEED or BREEAM scores does little more than pay lip service to sustainability. By choosing to score highly in some elements, while ignoring others for the sake of aesthetics is a pretty cynical approach. There are now environmental certification protocols that look specifically at buildings, rather than products or operations. A good example is the new Planet Positive Building certification standard, launched in January 2012."
Unfortunately, with architects striving to design buildings with smaller carbon footprints, the occupant element can sometimes be ignored. Too often, buildings are designed beautifully and efficiently, but they alienate the people that work in them.
"The design should be about how the space works," says Craft. "Environmental benefits gained through design can be easily reversed by dissatisfied people not working to their full potential. A carbon footprint normalized against revenue-a measure of the intensity of the carbon footprint-might end up a lot higher than expected due to people in the building being unhappy, unproductive or even unwell. I recommend that clients meet with designers for a site consultation to measure light levels and offer an interior landscape design for the space geared toward reducing a building's carbon footprint."
At Wausau, Fronek emphasizes the importance of the design process proceeding from the outside in. "Climate, building purpose and occupancy are among the contextual variables established at the onset of integrated design," he says. "Site, building orientation and programmatic constraints are then considered to develop a 'first-pass' window and curtainwall layout. Highly efficient buildings should be oriented along an east-west axis and maximize north- and south-facing glazing. Open plan offices and light-colored interior finishes help distribute daylight more deeply within the building. Most experts concur that load reduction comes first, followed by mechanical and lighting system selection and optimization to meet these loads efficiently. Only then is the need for on-site renewable energy generation using technology, such as photovoltaic (PV) power, sized and located."
Exceptional energy efficiency
Designing more energy-efficient buildings will automatically reduce building carbon footprints. "When you consider 85 percent of the building cost over a 30-year period is in operation and maintenance, the real goal should be to design low-maintenance buildings with exceptional energy performance," says Wes Brooker, marketing development manager, American Buildings Co., Eufaula, Ala. "This is done through maximizing insulation in the building shell, using energy-efficient windows and lighting, and high-performance HVAC systems.
"If the total cost of a building is $100 million over 30 years, the building itself only costs $15 million. A building shell is typically 25 percent or less of the initial building cost, which comes to $3.8 million or only 3.8 percent of the total cost over 30 years. Insane cost cutting on an initial structure, which we have seen in recent years, can cost dearly over a 30-year period. In the words of an old Fram oil filter commercial, 'pay me now or pay me later.' In the case of a building, you pay, pay, pay, pay for 30 years."
To correctly design an energy-efficient building envelope-including the metal panels, curtainwall and framing-a system approach is critical because these components are integrated with each other. When looking at insulation, the design must not only maximize the amount of continuous insulation required to minimize thermal shorts through the components, but also ensure the design includes solutions to minimize air leakage that can occur at the many junctions between these components. Designers must look at how these integrated components are configured. "Recent 'hot box' testing of metal roofing assemblies by the Metal Building Manufacturers Association (MBMA) and Oak Ridge National Laboratory (ORNL) showed the overall tested R-value of the assembly can be directly affected by the size of thermal spacers and panel clips," says Todd. "In some cases, although the calculated R-value was high, the tested R-value could be up to 30 percent lower. However, when using THERMAX insulation with thick thermal spacers and panel clips, the installed R-value was closer to 80 percent of the calculated value. The learning is that designers should pay close attention to the whole envelope design."
With more than 80 percent of commercial buildings in the United States being at least 10 years old, building owners and facility managers are increasingly deciding to retrofit their buildings to save energy and reduce carbon footprints. "Even though a product or solution may save energy, the important factor often overlooked is how much energy did it take to manufacture, and therefore what is the overall reduction in carbon footprint it will have on a building," says Giblin. "Solar Gard window films are both carbon smart and cost effective, consume up to 30 percent less energy for cooling at a fraction of the cost of installing new windows and are the only window films to achieve an EPD. This declaration verifies that they are carbon negative, i.e. they save more energy than they take to produce."
The footprint's future
What's coming? CO2 emissions from buildings are projected to grow faster than any other sector in the next 25 years. But, a significant advantage the metal building industry has over conventional construction is that it controls the entire envelope, making adjustment to new, tougher energy and lighting standards easier.
"This avoids the 'Keystone Cops' syndrome in conventional construction where everyone in the supply chain points at someone else for the envelope not performing," says Brooker. "LCA and Life Cycle Inventory (LCI) will also become a way of life in the next three to five years. Construction product industry associations are working with consultants and other experts to determine LCI values for the products they produce. Measuring and reporting the carbon footprint of various products will become the norm. Steel has a distinct advantage with LCA/LCI due to its long life and recycling characteristics."
Legislating the footprint
The U.S. Department of Energy (DoE) encourages building owners and facility managers to concentrate on energy efficiency to reduce carbon footprint. DoE policies such as the Section 179d Tax Credits support that direction. The Energy Policy Act of 2005 (Public Law 109-58), signed by President George W. Bush, created a tax deduction for constructing energy-efficient buildings. The Emergency Economic Stabilization Act of 2008 extended the expiration of this tax deduction to Dec. 31, 2013. This tax deduction is between $0.30 and $1.80 per square foot (of building floor area) depending on the type of systems installed.
The full tax deduction is available to owners of both new and existing commercial buildings where the installation of interior lighting systems, HVAC systems, building envelopes and service hot water systems reduce the total annual building power and energy costs by 50 percent or more compared to ASHRAE 90.1-2001 minimum requirements. A partially qualifying property will be able to receive a portion of the tax deduction as long as one of the systems saves at least 16.7 percent in energy and power costs. "In some countries, governments make significant difference in reducing building carbon footprint," says Kenneth Freeman, head of Ambius University and international technical director for Ambius in Harlow, Essex, United Kingdom. "For example, the UK Climate Change Act was the world's first piece of environmental legislation setting legal targets for reducing GHG emissions. The use of planning controls to encourage greener buildings is also important; developers might just find that green buildings get an easier path through the planning process."
Energy codes like ASHRAE 90.1 "Energy Standard for Buildings Except Low-Rise Residential Buildings" and the International Energy Conservation Code (IECC) now require continuous insulation to minimize thermal bridging in certain climate zones to help improve overall thermal performance of walls. Designers now have to address air leakage by detailing mandatory air barriers.
"Taken together, these measures do have a direct impact on reducing building carbon footprint," says Doug Todd, market manager, commercial construction at Dow Building Solutions, The Dow Chemical Co., Midland, Mich. "Government has provided support for states to adopt these more progressive codes to accelerate adoption and we are starting to see results in the field. As a manufacturer, we are encouraged that these agencies are recognizing the value of improved building envelope design, reflecting the supporting science.
This article first appeared in Metal Architecture.