Energy efficiency: The heat is on

by sadia_badhon | March 24, 2021 11:06 pm

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by Thomas Renner

The impact of buildings on the environment is surprising, but nonetheless, critical. Buildings consume 40 percent of the globe’s energy use and are responsible for 40 percent of emissions both worldwide and in the United States. More and more buildings, new and old, are transitioning to low-carbon/carbon-neutral construction. Everything from residential flats to commercial high-rises is being specified with sustainability in mind. The United Nations’ goal is to transition to zero emissions by 2050. The focus is more in the urban areas, where experts predict over 66 percent of the population will reside in 2060.

What does this mean for architects and specifiers? Well, for one, change. Many are already adapting. With several government entities and groups pushing to address climate change, there is no more stalling. Change is coming, and it is going to be swift, certain, and enduring. Maybe, after years of fits and starts, the movement toward energy-efficient construction will have the staying power of a marathon runner.

“It has taken different priorities over the years,” said Daniel Overbey, AIA, director of sustainability at Browning Day in Indianapolis. “We have become aware of just how much global warming and greenhouse emissions come from the building sector. It is a huge piece of the pie, and if we can do something about it, now is the time. Dollar for dollar, the best place to invest is in the architecture. We now have the tools that can see in real-time the relative difference in performance.”

The 2030 Challenge

The genesis of the movement for environmentally friendly architecture started out, oddly enough, on the basketball courts of Pratt Institute in Brooklyn in the 1960s. Edward Mazria, who was recruited to attend the school because of his on-court prowess, decided to enroll in the school’s architecture program.

Mazria spent his career in the industry, and has established himself as one of the leaders in architecture and renewable energy. In 1979, he published the Passive Solar Energy Book, which is still in use worldwide.

A transitional moment occurred in 2003, again in an unlikely setting. During a visit to Disneyland with his family, Mazria was reviewing material and saw a graphic that leaped off the page.

“I discovered the built-in environment is responsible for 70 percent of all greenhouse gas emissions globally,” Mazria said in an interview with the nonprofit Encore. “Once I discovered that, Architecture 2030 was born.”

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A nonprofit, Architecture 2030’s predominant objectives are to achieve a dramatic reduction in the energy consumption and greenhouse gas (GHG) emissions of buildings, and advance the development of sustainable, resilient, equitable, and carbon-neutral building communities.

“Once I discovered that we in the building sector were the driving force in greenhouse gas emissions, I asked are we going to do business as usual or are we going to address an issue where the planet is at stake,” Mazria explained.

Mazria closed his architecture practice in 2006 and is now the CEO of Architecture 2030. He has developed the “Roadmap to Zero Emissions,” and is currently working with cities across the U.S. to develop pathways for dramatic GHG emission reductions by 2050. While Mazria is not the only architect to connect the dots between buildings and energy performance, he is one of the most universally acclaimed for his pioneering work.

“What Ed discovered was a big piece of the pie,” Overbey said. “What we discovered in the architectural and building community is just how much global warming and greenhouse emissions come out of the building sector.”

Change is coming

In September 2020, the U.S. House of Representatives reviewed 150 amendments related to clean energy. The proposals included items such as:

• $1.2 billion in funding for a Home Energy Savings Retrofit Rebate Program at the federal and state level;
• $100 million to grant states funding to improve energy efficiency in public buildings; and
• $225 million for the Energy Department to assist states in implementing building energy codes.

The bill also includes funding for renewable energy.

The UN is tackling the problem, too. In a 2020 report, the UN said emission from the material cycle of residential buildings in G7 countries and China could be reduced by at least 80 percent in 2050 through a series of material efficiency strategies. The panel’s modeling unit said greenhouse emissions could be reduced by 350 million tonnes in China, 270 million tonnes in India, and by 170 million tonnes in G7 countries between 2016 and 2060 by designing with alternative materials.

The world has taken note of the building industry’s impact on the environment, and unlike previous concerns, there is a commitment to aggressively tackle the issue.

Identifying the problem, however, is only the first step. Rolling up the sleeves, delivering the details, and manufacturing the necessary components are the hard parts. That is where architects, construction teams, and suppliers come in and work with building owners to meet their needs while addressing net-zero strategies.

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There are a ton of factors to consider. Building codes, costs, footprint, environment, construction teams, and many other choices have to be made. Adding demands on energy goals creates an extra challenge. Everything from roofing and façade materials to cladding has to be considered along with many of the building’s interior elements. Building owners also have their say in what they want included in the structure. Building design is like one big Rubik’s Cube, and factoring in energy demands adds another dimension to consider and solve. Like the solution to the pesky cube, every detail must align perfectly.

“The first step in designing a building is to find out what the goals are,” Overbey said. “What are we trying to accomplish with the façade? Then we have to talk about the definition of high performance. We will want to be better than the standard. But what is the standard? If we aim for a much higher percentage than the standard, what is the return on the investment?”

The envelope, please

In the quest for more energy-efficient buildings, architects usually tackle the envelope first. The primary objective is to ensure a tight envelope to keep out wind, rain, and moisture.

“The highest performance envelope is one without windows,” Overbey said. “Generally, glazing systems are the weakest links for energy efficiency, but what would a windowless building be like for users? Architects cannot overlook the human element of buildings for the sake of performance.”

In the earliest design stages, there is often debate about how much glass to include on a particular project. There is hardly a building in the world without windows. Windows are 10 times less energy-efficient[4] than the wall area they replace, and an average home may lose 30 percent of its heat or air-conditioning energy through its windows.

“It is the tension of the two sides,” Overbey said. “You have to balance the human experience with the energy equation. The most well-insulated envelope is one that is basically a cocoon. It is important to find that sweet spot where you can specify a glass with a treatment that will also reduce the amount of heat transfer.”

Channel glass

Architects can enhance a building’s energy efficiency with channel glass. The material is preferred by some architects, as it requires minimal framing, which reduces thermal bridging. In buildings, thermal bridging occurs when conductive materials provide a bridge for energy to transfer across a thermal barrier. The bridge leads to energy loss and the potential for condensation. In colder climates, internal heat will seek to transfer to the colder side of the envelope, resulting in more energy needed to maintain room temperature. In warmer climates, exterior heat will seek to enter the envelope. Up to 33 percent of a building’s energy could be lost through thermal bridges.

Channel glass also adds insulation with its double-glaze assembly and insulation inserts that are inside the channels. It provides daylighting, thereby reducing energy demand.

At Franklin & Marshall College in Pennsylvania, Steven Holl Architects used a double layer of channel glass with translucent insulation in the school’s visual arts building. The channel glass traces the façade in vertical facets. The rest of the building envelope is either stucco or clear glass.

Translucent channel glass also provides soft illumination for art students working inside during the day and creating an ethereal aura at night.

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Rainscreens

Another method to help reduce energy dependency is through the use of rainscreens. A rainscreen system’s primary objective is to protect the envelope and deter rainwater from falling into a building’s exterior wall. By preserving the integrity of the structures, rainscreens safeguard their embedded carbon energy. They are also effective in managing air infiltration and heat transfer.

The rainscreen promotes energy savings due to the air cavity between the cladding and the exterior façade of the building, allowing for continuous ventilation. The enhanced ventilation improves the durability of the structure, as it remains dry. It also prevents heat buildup behind the cladding, making cooling the building easier in summer months.

Inova Schar Cancer Institute in Fairfax, Virginia, has a vertically and horizontally shingled glass rainscreen system. The rainscreen has an aesthetic and lighting role, but the shingled glass system acts as a permanent moisture shield.

The cladding’s continuous horizontal steel substructure sits atop a layer of rigid insulation, and has the ability to stop more than 90 percent of wind-driven rain from reaching the air and vapor barrier of the building. It also doubles as an anchor for the light-emitting diode (LED) lighting cable.

The shingled glass was engineered with a structural interlayer to use relatively lightweight 10-mm (³/₈-in.) glass for large, 1.5 x 1.8-m (5 x 6-ft) cladding panels. The interlayer reinforces the glass so it can span under the imposed wind loads. The vertically and horizontally shingled panels are held in patented compression fittings, independent of each other, for ease and speed of installation.

Designing an energy-efficient building envelope requires extreme integration that accounts for sun positioning, building materials, climate, and the quality of construction. The envelope is just one part of the overall equation. While it may be a starting point in most projects, the ultimate efficiency is captured by the meshing of a wide range of products and components.

“An integrative, holistic approach is the best way to make sure the building is designed for maximum energy efficiency,” Overbey said. “When you look at everything, even the massing, we can get a sense of how it is going to be.”

All in

More and more architects are now embracing energy-efficient design. Forty-one percent of all U.S. architecture firms have committed to zero-carbon design by 2030.

Architects are not the only ones. The U.S. Green Building Council (USGBC), National Governors Association (NGA), and others have adopted the goals of the 2030 Challenge. Even the United States government now requires new federal buildings and major renovations to meet 2030 Challenge standards.

There are still challenges ahead. In the world of energy-efficient construction and building materials, manufacturers are just scratching the surface of what is needed for a permanent and complete overhaul. Energy savings must improve dramatically, and there is also a need for more diverse sources of energy efficiency.

Measurement is also essential. In 2013, the University of California Davis (UC-Davis) pledged to reduce its net GHG emissions for its physical plant and vehicle fleet to zero by 2025. The university monitors 200,000 data points that show how efficiently energy is being consumed. The details will help UC-Davis make strategic decisions for new energy systems and future purchasing decisions.

Perhaps the most pressing challenge, however, is the need to pivot quickly. The environmental impact on the planet has been well-documented, and the time is at hand where solutions need to be found and installed quickly. The planet is asking for a swift reversal in the way the global population goes about using its precious resources. Architects are on the frontline in ensuring that occurs.

Thomas Renner writes on building, construction, engineering, and other trade industry topics. He is based in Stamford, Connecticut. He can be reached at trenner@catalystmc.com[6].

Source URL: https://www.constructionspecifier.com/energy-efficiency-the-heat-is-on/

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