Years ago I was in a prototype green trailer design with bamboo floors that were being pitched as greener (that's how long ago) and a prospect walked in, looked at the floor and asked "How does this save me energy?" He was not alone; for many, energy conservation has been the driving force behind green design. First, it was because of the oil crisis of the seventies, about reducing consumption and eliminating dependence on foreign supplies; then climate change took over as the driving force, and the need to reduce carbon dioxide emissions.
Passivhaus, or Passive House in North America, is mostly about saving energy, and is one of the toughest standards of efficiency, using as little as 10 percent of the energy used by conventional buildings. They write on Passipedia:
But this raises the question: what do we mean by eco-friendly? I have always believed that there is a lot more to it than just primary energy. Others think so too; after I wrote a post about the embodied energy of materials, Passive House architect and writer Elrond Burrell tweeted a little summary that describes what he thinks is the best:
Passive Houses are eco-friendly by definition: They use extremely little primary energy, leaving sufficient energy resources for all future generations without causing any environmental damage.
1) Passive House energy efficiency + 2) low embodied energy + 3) non-toxic + 4) walkable.
What would it take to develop a standard that did all this? Let’s have a look. We could call it the Elrond standard. Or if it is based on Passive House and they all ready have a Passivhaus Plus, we could go all Orwell and call it Passivhaus Doubleplusgood.
1) Passive House energy efficiency
This one is easy; Passive House, or Passivhaus is a very tough energy standard, as noted above. There are other high efficiency standards, and a lot of people are pushing Net Zero Energy Buildings with on-site renewable resources like photovoltaics that in the course of a year generate as much power as they consume. But for at least part of the year, and even part of the day, the NZEBs are relying on the grid, and much of the grid still runs on coal. There are lots of other energy efficiency standards, including Energy Star, but Passive House is big, smart and tough.
When the crunch comes, when the power goes out, an NZEB won’t keep you cool or warm for long, unless you have lots of batteries. Super-insulation will; that’s why I continue to believe that investing in insulation is better than solar panels, and have come to love Passive House.
2) Low Embodied Energy
It has been said that embodied energy and carbon, which goes into the materials used to build a building, isn’t that relevant when compared to operating energy, which overwhelms it in short order. But in super-insulated buildings like Passive House, with very little operating energy, (and lots of insulation), embodied energy has a much bigger impact. The Passipedia says that “The additional energy required for their construction (embodied energy) is rather insignificant compared with the energy they save later on.” This is true, but it still matters. Some building materials, like concrete and foam insulation, embody huge amounts of carbon and energy. Aluminum has been called solid electricity; urethane foams solid gasoline and cement is a whole other story.
The Living Building Challenge, another certification system, requires that carbon offsets be bought to compensate for the embodied carbon and energy in the building. That could get expensive if the wrong materials are chosen.
Embodied energy is tough to actually get a handle on; recycled aluminum usually gets a pass because it uses 95 percent less energy than virgin aluminum, but as Carl Zimring noted in his book Aluminum Upcycled, as long as there is more demand for aluminum than there is supply of recycled aluminum, that using recycled creates demand for virgin. It “does not close industrial loops so much as it fuels environmental exploitation.”
The Norwegian Powerhouse standard takes embodied energy into account, and generates enough power to compensate for it over the life of the building. That is tough and relies on a lot of rooftop solar. The Passive House system is based on hard numbers; perhaps we need a hard per square meter embodied energy limit.
3) Non-toxic or Healthy building
While Passive House promises and delivers clean fresh air all year round with its mechanical ventilation system, it is agnostic about what building materials are used, what the house is actually made of.
But there are many materials that should not be in a home or office. There are flame retardants, phthalates, volatile organic compounds, chemicals like formaldehyde that can make the occupants sick. There are materials that are toxic in their production or with a huge global warming impact.
For instance, some insulations are made with blowing agents that are really destructive; XPS or extruded polystyrene is made with HFC-134a, a blowing agent that is 1300 times as bad as Carbon Dioxide; others are no worse than CO2. Engineer Allison Bailes thinks that this blowing agent issue is overblown, so to speak, but even if the blowing agent is fine, foams are full of flame retardants and the components are mostly made from fossil fuels. Even the soy based foams are only 15 percent soy substituting for petroleum products.
Then there is the fuel that is often used for water heating or cooking; I have been in passive houses with gas stoves (not common, admittedly) and gas hot water heaters. But we recently wrote about how residential use of fuels is contributing to poor air quality, illness and deaths, and I simply can no longer see how burning any kind of fossil fuel in a house can be considered green anymore.
Whenever possible, a building should be built with materials that have zero impact on the occupants health, the neighbours, the people who made the product. Products made from renewable resources are even better.
The Living Building Challenge is terrific on this; perhaps this should be modelled on their red list and healthy building criteria. The Well Building standard is worth a look too, although it is currently just for commercial buildings. We are also doing a series on the importance of healthy homes. m
This is perhaps the most difficult and the most contentious. Location matters, and has been shown to be a bigger contributor to energy consumption than just about anything else. It is transportation that is killing us. Planner Jeff Speck has shown that living in a walkable neighborhood saves as much energy in a week as changing all your light bulbs does in a year. The Urban Archetypes Project demonstrated that you could live in leaky 100 year old walkup apartments and still use less energy than someone living in a new house in the suburbs.
Many believe that with electrification we will all be able to live in our suburban houses with solar shingles on the roof and batteries and electric cars in the garage. But it isn’t really true; it doesn’t scale. It still requires a huge amount of energy and the suburban model still requires land, roads, using resources that still have big impacts. You can’t build green passive houses in the suburbs without concrete roads and pipes.
Walkability implies density- you have to build enough that is close together so that you can support shops and businesses that you can walk to. It implies multifamily buildings, but not exclusively; there are lots of older walkable neighbourhoods in North America, streetcar suburbs like the one I live in, where it is dense enough to support a nearby main street which is busy enough to still support a streetcar.
But walkability, as a criterion, would probably save more fossil fuels, infrastructure and carbon emissions than any other single factor.
Do we need a new standard?
There’s LEED, WELL, Powerhouse, BREEAM, Energy Star, Living Building Challenge, PHIUS and more. Some are playing with what they call the Pretty Good House standard, which I think is pretty interesting. Designers can pick and choose from any of them, really.
But I think we do need a standard, particularly in the residential sector, that applies the rigor and math that Passive House applies to energy to these other factors of embodied energy, health and walkability. Perhaps it should be the Elrond Standard, since he inspired this. Or perhaps the Passive House doubleplusgood. Because energy efficiency isn’t enough anymore.