This blog post is an overview of our recent Building a Sustainable Future virtual event. A recording of the event can be found at the bottom of this page.

How we choose to design and build the buildings of the future will have a major impact on energy use and occupant wellbeing. In the U.S., buildings account for around 40% of total energy consumption, 73% of electricity consumption, and 14% of our water consumption.Designing efficient buildings can help us lower our energy consumption and keep our carbon footprint down.

Americans also spend around 90% of their time indoors (and probably even more than that since the start of the pandemic), and the design of these spaces where we spend most of our lives has the ability to impact our health and wellbeing.

A great way to ensure that buildings run efficiently, have a low carbon footprint, and promote health and wellbeing is to get projects certified by a building certification program that strives to achieve these goals.


The most popular of these certifications is Leadership in Energy and Environmental Design, or LEED. LEED has certification standards for all kinds of projects from single family homes, to bigger projects like schools and office buildings. There are also LEED programs for interior design, neighborhood development, and much more.

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LEED certification takes many factors into account from access to transportation to energy and atmosphere! Photo credits: Kent Hicks Construction Co.

The majority of the projects promote efficiency and wellbeing through 6 main categories: location and transportation, sustainable sites, indoor environmental quality, water efficiency, materials and resources, and energy and atmosphere.

Achieving the goals in these 6 main categories, as well as other LEED program goals like innovation and regional priority will make buildings greener and more sustainable.

Passive House

Another popular building efficiency standard is Passive House. Passive House is a building standard that is truly energy efficient, comfortable, and affordable at the same time.

Just like LEED certification, there are specific standards that must be met and approved by a certified Passive House rater in order for a building to qualify as a Passive House.

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Passive house is an international high performance building standard that really focuses in on energy efficiency. Check out the attached webinar for a tour of this beautiful passive house courtesy of Mount Holyoke Associate Professor of Physics, Alexi Arango! Photo credits: Alexi Arango

There are two entities that offer Passive House certification, Passive House Institute (PHI) and the Passive House Institute of the United States (PHIUS). The biggest difference between the two is that PHIUS has customized heating and cooling demand thresholds depending on your climate, whereas PHI assumes a northern European climate.

There are four concrete passive house requirements, mostly concerned with energy efficiency.

Living Building Challenge

Lastly is the Living Building Challenge (LBC). Living Buildings strive for net-zero energy, are free of toxic chemicals, and lower their energy footprint many times below the generic commercial structure.

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The R.W. Kern Center is a certified Living Building on the campus of Hampshire College. One of only 23 fully certified Living Buildings, The Kern Center meets high standards for energy, water, materials, place, beauty, equity, health, and happiness. Photo credits: The Kern Center

LBC projects achieve this goal by adhering to 7 performance categories, or petals. These petals are energy, water, materials, place, beauty, equity, and health & happiness. The petals are used to represent a building that is as efficient as a flower.

Environmental Impact

There is a lot to say about how these building standards reduce the environmental impact of buildings but we’re going to focus on two areas—energy efficiency and embodied carbon.

We can compare the energy efficiency of these certification programs by looking at HERS ratings of completed projects. A home’s HERS rating is a measure of its energy efficiency; the lower the score the better. Check out the HERS website for more info on the rating system.

Just for some context, the average new home in Massachusetts has a HERS rating of around 70.

HERS ratings of LEED certified buildings vary a lot but they typically fall within the 0-70 range, and Passive House buildings typically fall within the 0-40 range (making them between 30-70% more efficient than an average new Massachusetts home).

This difference in range of HERS ratings illustrates the main difference between LEED and Passive House. Passive House is much more focused on energy efficiency, while a building can be of average efficiency but still get LEED certified if it really commits to other areas of the program.

Embodied Carbon

Another big contributor to a building’s carbon footprint is the embodied carbon in its materials. A lot of emissions are released in the mining, processing, shipping, and eventual disposal of building materials. A building’s environmental footprint can be greatly reduced by using building materials with low embodied carbon.

The best way to reduce embodied carbon is to reuse building materials. When demolishing or redoing a home, it is possible to do so while salvaging materials and appliances in the home in a process called deconstruction. CET operates a store in Springfield, MA called EcoBuilding Bargains where you can donate and buy high quality reclaimed appliances and building materials for a fraction of their original price.

If reclaimed materials aren’t an option, there are steps that builders and designers can take to use materials with lower embodied carbon.

The best way to do this is to try and limit the use of steel and concrete. These materials account for around 8% each of total world greenhouse gas emissions.

Builders and architects can use lower carbon concrete, or limit use of concrete in the building process, but one of the best ways to reduce a building’s carbon footprint is to build with wood.

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Cross laminated timber (CLT) is made by smaller pieces of wood stuck and pressed together in a crosshatch pattern. CLT and other types of mass timber make for sturdy, flame resistant, and environmentally friendly building materials. Photo credits: APA – The Engineered Wood Association

Sustainably farmed wood has a much lower carbon footprint than concrete and steel. It has an even more positive impact when you consider the amount of CO2 that wood sucks up and stores when it grows.

There are a host of new construction grade wood products called mass timber that make constructing tall buildings with wood safe and cost effective.

Economic Benefits

Building green can also be good for your wallet. Green buildings result in significant savings across energy, trash, water, and maintenance costs. LEED certified buildings on average save 25-30% of energyopens PDF file compared to traditional builds, and Passive Houses can generate lower lifecycle costs since they reduce heating costs by 75-90%.

Sustainable buildings can also generate increases in asset value over traditional buildings. Green home owners can see a 10% or greater increaseopens PDF file in the asset value of their home, as well as building values around 7.5% higher than comparable homes.

Health and Wellbeing

In a study conducted on a business moving from a traditional building to a LEED certified building, researchers surveyed workers pre and post move and found that workers were less absent due to asthma and respiratory allergies, they were less stressed, and more productive in the LEED certified building.

These improvements were mostly due to the improved ventilation, natural light, and biophilic design elements that the LEED program requires.

Learn more about CET’s LEED and Passive House programs, as well as other High Performance Building projects here.

Check out EcoBuilding Bargains for reclaimed building materials!