As interdisciplinary cooperation between architects and engineers becomes more common, building envelopes are increasingly incorporating renewable energy options.
By Carol Brzozowski
Building envelopes are encompassing an increasing use of renewables as interdisciplinary cooperation between architects and engineers, and an emerging preference for outcome-based designs is ramping up. Addressing renewables and Leadership in Energy and Environmental Design (LEED) certification, Joe Murray, a principle design architect with IDC Architects, a wholly owned subsidiary of CH2M Hill, notes that photovoltaic (PV) systems are being integrated into the building envelope to serve as both an energy producer and an energy gatherer.
“There are films you can put inside or outside the glass that gather energy,” says Murray. “You can use PV panels as solar shading devices, not only to shade windows from the hot summer sun, but also to gather energy.”
Murray says that although using PV to gather energy is a “great opportunity,” it has a long payback, and his company is working with manufacturers to reduce costs.
“The reality is we can only do as much as our clients let us do,” he says. “We have to continuously build better arguments for why they should be looking for ROIs [return on investments] longer term.”
The marriage between onsite renewables and energy efficiency makes onsite generation “highly feasible.” says Doug Pierce, a senior associate with Perkins+Will.
A colleague of Pierce’s sells energy efficiency via performance contracting and solar PV/solar thermal to building owners.
“Clients want that ‘curb appeal’ of solar,” says Pierce. “He [Pierce’s colleague] tends to open with onsite renewable generation, then follows with the importance of doing both energy efficiency plus onsite generation. Once clients comprehend that they can increase the total percentage of onsite generation by being more energy efficient, they find it even more appealing, and, by selling solar plus efficiency, he delivers more onsite renewable solar than he would have without the efficiency.”
Perkins+Will was the first international architectural firm to adopt the 2030 challenge. Issued by the American Institute of Architects, the challenge is for architectural firms to make it a standard practice by 2030 to design and construct climate-neutral buildings—buildings that do not use greenhouse gas emitting energy to operate. The voluntary commitment is to reduce energy consumption across a firm’s entire portfolio, not just for projects seeking green building certification.
“We are developing our capacity to do very early energy analysis work,” says Pierce. “We get real-time feedback on where we’re headed while we’re still doing sketches and conceptual work, and before the engineers typically get deeply engaged in the project. That’s when major decisions in efficiency are made.”
Pierce says the key is to identify what measures have the greatest impact and are fastest in terms of payback.
“There is less focus on envelope R-values and more on reducing internal heat loads through various methods such as daylighting and other kinds of equipment loads and measures that can have a faster payback,” he says. “Then there’s a moment where the paybacks and impacts shift over to having more focus on the building envelope and its R-value and insulation.”
Daylighting and using narrower floor plates is becoming more common, Pierce says.
“With more envelope relative to square footage, that’s when insulation values of the buildings start to become more prominent,” he adds.
Pierce finds that while energy models can be helpful and get more sophisticated over time, “they don’t necessarily tell you what kinds of energy impacts are going to happen because of microclimate issues inside of the building” that may cause employees to crank up the air-conditioning to accommodate those people sitting in “too warm” areas, thereby impacting the overall system efficiency.
While computer analyses are important, sometimes the effectiveness of a given measure isn’t apparent until after the measure is employed, Pierce says.
“Designing the buildings to be high performance is only the first step,” he says. “The second is to go through a full measurement verification period afterwards in which you tune the building up far beyond what happens in the standard commissioning. Then you learn from that cycle, that this design activity was not as efficient or effective as was hoped, or that it would be better to do it this way.”
The use of renewables is an important part of the energy efficiency effort, Pierce says.
“From a LEED standpoint, there are a lot of points connected to energy efficiency measures,” he says. “Even if you do a stellar job of it, it’s not something people notice much. But they pay attention to a solar panel or a wind turbine.”
Each project designed by Perkins+Will incorporates the maximum amount of energy efficiency. The company then incorporates renewables—not only to provide energy, but also to draw attention to the “energy efficiency” story, Pierce says. According to him, there are “very high” costs to be paid for non-renewable energies such as fossil fuels and nuclear power, including externalized costs placed on society. With the cost of renewables coming down, learning how to use renewables and integrating them more into design is “really essential,” he adds.
“I would expect that in five years, there’s going to be some extremely cost-competitive photovoltaic options that will really energize that aspect of designs, maybe even sooner,” he says. “The new technologies and breakthroughs happening on that front will bring PV clearly into a very competitive place.”
Pierce also sees great promise for solar hot water.
“That’s a work horse in terms of renewable energy and underutilized as a great payback for domestic hot water,” he says. “You’ll see more solar hot water applications coming on line as energy costs creep up.”
Whether it’s through renewables, fossil fuels, or nuclear power, “no matter what we do, we simply won’t be able to generate enough of that kind of energy to solve our challenges,” says Pierce. “We have to focus on getting efficient equipment in the buildings. Getting our building envelopes better designed is the next step many of us are going to be taking.”
Steve Doub is a project architect the Miller Hull Partnership with an extensive background as a building envelopes consultant. The Miller Hall Partnership designs a range of buildings, from commercial to residential. The firm also is a member of the American Institute of Architects’ 2030 commitment.
The primary focus is on reducing carbon footprint, as a built environment represents 49% of energy consumption in contract to 28% for transportation and 23% for industrial, says Doub.
“The building envelope is pretty critical,” he says. “Not only are there traditional views of it being like a thermal blanket around a building and a way to keep air infiltration down, but a lot of our projects now are becoming interconnected with other disciplines, so we have to have an integrated team to provide input to design the building envelope.”
A building envelope largely contributes to achieving a balance in daylight, thermal comfort, and sun shading, Doub says.
An interactive envelope with exterior sun shades can track the sun to maximize daylighting while minimizing heat gain.
“On the glazing side, there are always more coatings coming out. They’re always trying to improve the U value of the glazing itself, but also keeping the solar heat gain down while allowing visible light transmittance,” he says. “A lot of those are competing criteria.”
With insulation, Doub says he sees more building code requirements for minimizing thermal breaks through the envelope and minimum thresholds for penetrations through the insulation.
“We’re seeing not just a prescriptive nominal U value, but outcome-based requirements based on test data of actual assemblies or having them model that,” he says.
Especially with a net-zero project, no individual component drives the entire equation, Doub says.
“We measure the energy utilization index, which is measured in BTUs per square foot per year,” says Doub. “As part of the 2030 commitment, there’s a requirement to get performance data from the building after the occupants are in, rather than when you’re going for a permit and meet a certain prescriptive requirement.”
That post-occupancy feedback enables designers to make better-educated decisions about cost effectiveness of energy efficiency measures, notes Doub.
While today’s strategies focus on a tight envelope, “you want to be able to manage the air exchanges of the building so it’s not happening in an organic way through the envelope,” adds Doub. “You can control it through the mechanical system or through a window.”
Also, there is a range of occupant preferences, which must be weighed in balance with the energy use of the building, he adds.
Doub says energy codes are becoming more stringent and outcome-based.
“In Seattle, instead of having just prescribed air changes, you have to test the envelope with a blower door to confirm it,” he says. “It’s going to get to the point where the next step is to have a way to measure the outcome before you get your certificate of occupancy.”
In an effort to achieve sustainable building envelope energy efficiency, renewables such as solar panels are appearing on more roofs, with building owners taking advantage of incentive programs to fund those efforts. New Jersey is a leader in the nation for such programs. Langan Energy Solutions (LES), a solar integrator and energy efficiency company in Elmwood Park, NJ, recently completed an 80-kW rooftop solar system for an office building managed by Bukiet Building and Management Co. in Clifton.
The installation on the 64,000- square-foot, three-story building is expected to save $12,750 annually in electricity costs, offsetting 10% of the building’s electricity load. Additionally, electricity gained from the 290 solar panels will offset approximately 28 tons of carbon dioxide (CO2) emissions annually.
|Photo: © 2008 Don F. Wong
|Photo: © 2008 Don F. Wong
Michael Bukiet, principal at Bukiet Building and Management, acknowledges that while the carbon footprint and electricity savings are a prime benefit, another advantage is that the building is more attractive to prospective tenants, because it’s being powered with clean technology.
Much of the return on investment is expected to be recouped within a few years through several federal and state incentives, and a total payback is estimated at less than five years. For example, the Section 1603 Treasury Grant Program covers 30% of the upfront costs, and the 2011 bonus depreciation allows system owners to depreciate 100% of the system value in the first year of its operation. Both programs are due to sunset at the end of 2011. The building owners also will benefit from the sale of Solar Renewable Energy Certificates (SREC), a state incentive representing the environmental benefit of solar. Solar suppliers can sell SRECs for 15 years from the date a system is commissioned.
Solis Partners, a developer and integrator of commercial solar power systems, recently conducted a solar installation for P&R Fasteners, a contract manufacturer of specialty metal products for a variety of industries. The 254.8-kW rooftop solar installation at P&R’s corporate headquarters in Franklin Township, NJ, was capped with a “cord-cutting” ceremony to symbolize how the solar installation will offset nearly 100% of the 100,000-square-foot manufacturing facility’s electricity load, essentially taking it off the grid except for times when it must draw energy when there is little to no sun.
The system is expected to pay for itself in less than seven years. The rooftop solar-PV system consists of 1,400 Solyndra* panels that will generate approximately 295,000 kWh of electricity and eliminate more than 400,000 pounds of carbon dioxide emissions annually. The panels are lightweight glass cylinders with 360-degree PV surfaces, capturing direct sunlight from above, diffused sunlight from the sides and reflected sunlight from the roof. The rooftop solar PV system was integrated with a reflective white “cool” roof, which not only enhances the building envelope efficiency, but also increases the amount of solar production harvest.
P&R took advantage of the same incentives as did Bukiet Building and management. The solar installation is based on a financial decision, notes Doug Joyce, corporate controller for P&R.
“We look at it as a good investment for the organization with the stock market and other investment tools the way it is these days, and thought taking the funds we had on hand and investing it into ourselves made a lot of sense for us,” he says, adding that it has a favorable payback with “very little risk.”
P&R sought to size the system to the facility’s annual energy consumption.
“We made it as big as we could get it,” says Joyce. “We upgraded the type of panel we could put on our roof to make sure we got as much benefit as we possibly could. We maximized the footprint.”
In addition to the tax incentives, P&R was driven by the value of the SRECs. “Everyone’s jumping on the same bandwagon,” points out Joyce. “We’re hearing rumors there will be an overage of SRECs on the market in 2012, so the prices have dropped down quite a bit. Still, we think it’s a good investment for us, and, obviously, there’s a lot of benefit for the community and the environment.”
The building in which P&R is located is 25 years old so it was apparent the roof would need to be replaced relatively soon.
“One of the big benefits we saw was the cylinder product line that Solis was carrying works a lot better with the white reflective roof, and it’s part of the system, so we were able to bundle that as part of the total package,” says Joyce, adding that his company was essentially putting on a new roof at 70% of what it would have otherwise cost.
The solar installation is enabling P&R to invest the savings back into the company. For Solis Partners, the aim of every project is to offset as much of a client’s electrical consumption in enhancing the building envelope and employing renewables at the same time, says Jamie Hahn, managing director. Because the solar installation will offset a percentage of the client’s overall electrical consumption on an annualized basis, Solis Partners also seeks other facets of the day-to-day electrical consumption to provide a reduction to current usage, and deploys rooftop solar to get closer to 100% than by deploying just the solar aspect of the project.
Hahn believes much of the work going forward will be in retrofits.
“There’s not a lot of new construction going on,” he says. “We have to find means and methods to retrofit existing facilities in a way so that they’re energy efficient, and then size the renewable part of the project to that new load characteristic.”
Hahn says although installation costs of renewables is decreasing, there is still a need for incentives and subsidies to offset the high costs before “grid parity” is achieved.
In about eight years, he says, “we can start to get grid parity where the cost of solar electricity will be able to compete on its own without subsidies against other fossil fuel-related energy sources, because the cost of installed solar commercially at least is going down, and the cost of fossil fuel-related sources is going up and will probably go on up even more significantly once we start getting out of this economic recession.
“The people who got in early got the major benefit of the full sets of subsidies that were there that will continue to get smaller as we move forward,” continues Hahn. “Subsidies for lighting, building envelope enhancements, and solar are very dynamic. If you don’t have your finger on the pulse, it’s very difficult to understand at one spot in time how to take advantage of the most subsidies available.”
Hahn believes the proper way to approach an energy retrofit is to start first with the internal building—heating efficiency and lighting upgrades—to lower its overall demand profile and then properly size the solar PV. Add a new roof, and the benefits surge, he says.
Leveraging federal and state funds to do both the roof and solar at the same time creates a more energy-efficient envelope at the greatest cost savings, Hahn says.
“One of the major components of the building envelope that can be most easily addressed is the roof itself,” says Hahn. Solis Partners’ core competency is in working on large commercial industrial flat to low-slope roofs.
“In many cases, the roof system is the last thing people tend to look at, especially the way the economy’s been,” he adds. “Not only are they not doing preventative maintenance on the roofs anymore—it’s more or less when there are failure issues do they spend money to address them.”
Hahn calls roofs a “non-performing” asset. “You build it, it keeps you dry, but beyond that, it’s more of a negative, in the sense that you have to pay to maintain it and you have to re-roof it from time to time,” he says. “Now you have the ability with solar, and with states that have incentives, to turn that roof into a value-generating asset for that business.”
|Photo: Goshow Architects
Opposite and Above: The synergy between a building’s envelope and indoor measures, such as lighting, is illustrated where offices let in natural light, taking full advantage of daylight harvesting.
Those who intend to occupy a building for 10 years or longer would derive benefits from a roofing upgrade prior to deploying a solar facility on the rooftop, Hahn says.
Solis Partners has found that a light reflective roof system can reduce energy consumption in a building by 20% when used in conjunction with other measures.
“The white membrane can provide efficiency measures by itself from a cooling perspective,” says Hahn. “That’s why the R value or the insulation could potentially add to that.”
A lighting retrofit can add another 30% reduction for a total 50% reduction in energy usage, Hahn says; the upfront costs can be financed by leveraging available subsidies. To have to replace a roof after the installation of solar panels “is a big mistake, because who really knows with inflation and labor rates in 10 years, or how much it’s truly going to cost to take everything off the roof,” says Hahn.
The panels will not come apart and be able to be put back on as they did when they came out of the box, he adds.
“More importantly, you’re going to do this job in better weather, which is typically the time for the highest production of solar, so what is the revenue loss you’re going to experience above and beyond the decommissioning or recommissioning costs?” says Hahn. “You’re going to forego energy production, pay for the utility, and, more importantly, you’re going to be foregoing income.”
Solis Partners is seeking new ways to integrate solar into roof systems. A traditional solar panel on a flat roof can create a “sail” effect in wind events, Hahn says.
“It’s almost impossible to deploy a traditional panel on a lot of roofs unless you drill hundreds of holes and mechanically attach that system to the structure to the building,” he says. “Most building owners don’t want to put holes on a flat roof. Water does a very good job of finding the path of least resistance. It’s going to be interesting to see new technologies that are much lighter and can be deployed specifically in flat roof environments.”
Integrating solar into roof systems “allows us to open up other buildings that are out there without doing some significant structural reinforcement, which after that building’s construction gets very costly and the job’s typically not very economical,” says Hahn. “We’re at a point where new products need to become available.”
While officials at the Thunder Bay Catholic School District School Board in Thunder Bay, Ontario, had some initial reservations about engaging in a major solar installation, once it was done, “we never looked back,” says Tom Mustapic, associate director. The School Board had signed an agreement with Honeywell to install a solar PV system to help offset annual utility costs by more than $70,000 and deal with an aging infrastructure.
The system—funded by a renewable energy grant from the Province of Ontario—is expected to lower carbon emissions by 64 metric tons per year. The solar project augments two previous energy conservation and facility renewal programs. The savings, guaranteed by Honeywell through 12-year performance contracts, will be used to finance upgrades. The 50-kW photovoltaic system will consist of 272 roof-mounted solar panels that will provide power to Pope John Paul II Senior Elementary School. The solar installation will link to a sustainability dashboard that will give students and teachers access to real-time data and graphs showing the electricity the panels generate, as well as the impact on the school’s carbon footprint. An additional energy conservation program will incorporate roof-mounted solar systems at two other schools.
Previous facility renewal programs included such improvements as installing two 10-kW roof-mounted solar photovoltaic systems with sustainability dashboards for classroom learning and sealing the building envelope, doors, and windows with caulking and weather stripping to reduce the loss of warm and cool air. Combined, the upgrades are expected to cut electricity consumption by 2.6 million kWh per year and decrease annual carbon dioxide emissions by an estimated 900 metric tons.
Mustapic says the school district invested approximately $900,000 in the solar projects and took advantage of local incentives, generating more than $100,000 in energy revenue from the province and creating a short payback period.
“We see, over 30 years, this netting us more than $2 million, so this is a type of thing where you have to think longer term, and think big,” he says.
The savings can now be earmarked for other projects in the school system, such as the science curriculum, adds Mustapic.
“It’s been a positive from the standpoint of the community image we’ve been able to generate, from the standpoint of curriculum, and from a business standpoint, in terms of revenue we’ve been able to generate,” he says.
Daylight harvesting—as captured through window placement in a building envelope—is assuming a greater role in energy efficiency efforts. Goshow Architects wanted a sustainable redesign of the office space that drew upon natural light, as well as other measures that would help obtain LEED certification in Commercial Interiors. The synergy between a building’s envelope and indoor measures, such as lighting, is illustrated in a recent relocation of Goshow Architects to an 8,000 square foot building in New York City. The building consisted of perimeter offices and an open central area.
“We wanted the reverse,” says Amanda Langweil, director of sustainability at Goshow Architects. “We wanted to have our design studios along the perimeter to let in a lot of the natural light and to be able to take advantage of daylight harvesting. There are a lot of windows in the building, so it was a real benefit to be able to do that.”
Because the HVAC system is owned and operated by the landlord, the energy efficiency focus was on the lighting. Offices were switched to the center with open studios created along the perimeter, filling the space with natural light.
Goshow Architects incorporated Encelium’s Energy Control System (ECS) for the lighting. ECS allows for personal control, task tuning, daylight harvesting, smart time scheduling, occupancy sensing and load shedding. As a result, the strategy delivered a lighting energy consumption reduction of 66%, a lighting energy demand reduction of 51%, the elimination of nearly 40,000 pounds of CO2 emissions, and six points toward LEE-CI Certification.
“With the Encelium system, we have very different controls, one of the segments being daylight harvesting,” says Langweil. “Oddly enough, the majority of daylight comes from the south side, but unfortunately on our south side, we have a building next to us, so we don’t get a lot of sun from the south.
“But our north façade, there’s a new building across the street that is higher than us. We get a lot of good daylight from that façade without the glare that often comes from that south sun. The north side takes advantage more of the daylight harvesting and during a bright day, especially in the summer time, the north studio is usually 20% artificial light—the majority is natural daylight.”
Longweil praises the ECS for being a system that “does all of the controls and settings. We don’t have to touch it. Initially, we programmed the system how we want it to be and it does its own thing.”
Neil Schroder, director of sales for Encelium Technologies, points out that the biggest challenge these days is trying to keep a building’s operating costs from getting out of control. “Lighting regularly accounts for nearly 40% of a building’s electricity consumption, so it makes sense for owners to seek ways to improve their energy efficiency and ultimately lower their electric bills,” he says.
The six key energy management strategies of ECS can be integrated and deployed on a facility-wide basis, yielding greater energy strategies than if used independently, as has been common in the past, Schroder says.
ECS reduces lighting energy consumption by 50% to 75%, resulting in lower building operating costs and a return on investment within two to five years, Schroder says. “Additionally, you’re improving lighting quality, workspace ergonomics, and flexibility while promoting sustainability,” he adds.
Achieving energy efficiency through technology must be augmented with behavioral changes to be most effective, Schroder points out.
“Just as more building owners are taking the initiative to seek ways to reduce energy consumption, so should occupants,” he says. “In general, I think people are more conservative with their energy usage at home, as opposed to when they’re at work. But I believe that occupants of a sustainable building become more aware of their actions and can easily recognize the many benefits that stem from a lighting control system once they experience it firsthand.”
Author's bio: Carol Brzozowski writes on the topics of technology and industry.