By Marc Companion
Our homes and buildings are complex structures that have a significant impact on the natural world, our communities and certainly our pocketbooks. A lot of excellent work is being done to improve building efficiency and to create green buildings. What’s the difference between the two?
By way of example, let’s take a look at two building performance standards that excel at transforming the way we design our buildings: Passive House and the Living Building Challenge.
Passive House is a voluntary standard that sets the bar for high performance thermal energy efficiency and comfort in buildings. The concept originated in Germany and Sweden in the late 1980s as a way to develop improved building technologies and an integrated design process. Passive House buildings are ultra-low energy structures that require very little energy for space heating and cooling. Think of thermal efficiencies so great that, for example, you might be able to heat your home with only a few candles or just the body heat of your family.
A key to Passive House-certified buildings is that they are super-insulated, super-tight and well ventilated, thereby enabling thermal energy to be managed in a very refined way.
Consider space heating in the winter. The walls, foundation and other parts of the building envelope are so thermally efficient that very little heat escapes to the outside. The heat you generate indoors stays indoors. This allows designers to take advantage of the heat sources already within the building, such as waste heat from the operation of major appliances and lighting, and the recovery of heat from a warm shower. Occupants – both people and pets – also contribute toward energy production through the body heat we all emit continuously.
The result is a building with very small heating and cooling systems, which can dramatically reduce the structure’s carbon and ecological footprint. Passive House buildings are quite comfortable, too, because the indoor temperature varies very little over time.
Moving beyond energy efficiency, we begin to think about the other systems that are part of our buildings. How does the structure affect its surroundings? What is its impact on water resources? Does it have a healthful indoor air quality? How much energy and resources are associated with the building materials?
Such questions are at the heart of green buildings, where in addition to energy efficiency, attention is paid to whole building, its relationship with its surroundings and the entire life cycle of the structure.
Many of us are familiar with LEED certification of buildings, which is a program that uses a rating score and third-party verification to encourage innovative holistic design.
Beyond LEED is the Living Building Challenge, a rigorous performance standard philosophically grounded in stewardship, and it’s perhaps the hardest standard to achieve. Here is an excerpt from the introduction for Living Building Challenge Standard 2.1:
“IMAGINE a building designed and constructed to function as elegantly and efficiently as a flower; a building informed by its bioregion’s characteristics, and that generates all of its own energy with renewable resources, captures and treats all of its own water, and operates efficiently for maximum beauty.
“IMAGINE a city block or a college campus sharing resources from building to building, growing food, and functioning without dependency on fossil fuel-based transportation.
“IMAGINE true sustainability in our homes, workplaces, neighborhoods, villages, towns and cities – Socially Just, Culturally Rich and Ecologically Restorative.”
This model of a house boat embodies a variety of green building principles, one of which is energy efficiency. Passive solar design and low-e glazing help improve thermal efficiency, while photovoltaics produce renewable energy, and Energy Star equipment increases electrical efficiency. Beyond efficiency, the boat also has a green roof for food production and a cistern to capture rainwater. Constructed wetlands on-board use local species to treat wastewater generated by the boat, and also serve an ecological restoration function. Nutrient-rich lake water containing unwanted algae blooms is pumped through the wetlands, which digest excess nutrients to improve lake water quality. In the words of UVM students Brynna Barbour and Vanessia Lam who designed and built the model, “it’s a sustainable house boat design that is completely off the grid and is able to self-regulate while purifying the water that it calls home.”
Seven performance areas the Challenge, which it calls “petals”: Site, Water, Energy, Health, Materials, Equity and Beauty. Yes, the building must have aesthetic qualities as well! These Petals are subdivided into twenty “Imperatives,” of which each is mandatory and measured based on actual performance, not modeled expectations. The Imperatives include:
The “Site” requirements contain criteria for urban agriculture, natural habitat and car-free living.
The “Water” standard is net-zero water.
“Energy” is net-zero energy via renewable sources.
The “Health” standard includes criteria for a civilized environment, healthy air and ‘biophillia’ (ensuring a connection to nature and natural systems).
The “Materials” requirements prevent toxic chemicals per a “Red List,” and have criteria for embodied carbon footprint, responsible industry, appropriate sourcing, and conservation and reuse.
The “Equity” standard emphasizes human scale and humane places, democracy and social justice, and rights to nature.
The “Beauty” standard promotes beauty and spirit, and inspiration and education.
The Living Building Challenge illustrates how green building can be differentiated from energy efficiency. A green building approach incorporates a varying degree of the principles set out in standards like the Living Building Challenge, of which energy efficiency is one important strategy. But of course not all green buildings push the thermal-energy efficiency envelope as far as Passive House. We need both standards, and each offers exciting opportunities.
Marc Companion works at the Vermont Housing and Conservation Board in Montpelier and teaches a Green Buildings course at the University of Vermont.
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