My part-time employer, BuildingGreen, recently celebrated the overlap of National Poetry Month and National Architecture Week with a sustainable design haiku contest. I am not normally someone who writes poetry, but I quickly discovered that writing haiku was a great way to blow off years of accumulated steam from trying to build a Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates.. So I dropped everything and immediately started tweeting a string of cathartic haikus.
Many of my little poems require some basic knowledge of green building, so I am turning this into a teaching opportunity by annotating my wee œuvre below. Let the learning begin!
A punch in the nose
To the next one who tells me
“A house has to breathe.”
Whenever I tell people we're building an extremely tight house, someone always pipes up, "Well, a house has to breathe." Yes, and that's why we're installing a ducted heat recovery ventilator (HRV). An HRV is a a fresh-air system with pipes to the outside, and it has a heat exchangerDevice that transfers heat from one material or medium to another. An air-to-air heat exchanger, or heat-recovery ventilator, transfers heat from one airstream to another. A copper-pipe heat exchanger in a solar water-heater tank transfers heat from the heat-transfer fluid circulating through a solar collector to the potable water in the storage tank. that transfers most of the heat between the two streams.
Our HRV is 84% efficient, which means that in cold weather it will transfer 84% of the heat from the outgoing stale airstream into the incoming fresh airstream. Compare this to a leaky house, which gets fresh air and expels stale air through holes in the building envelopeExterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials., losing oodles of heat in the process.
Lately when people tell me a house has to breathe, I tell them that a human also has to breathe but we do it with lungs and a respiratory system rather than by punching holes all over our body. For some reason, this metaphor really makes an impression.
It's hard to believe, but there is still a lot of unsustainable logging going on these days. Siding and decking are particularly bad, since it often comes from old-growth cedar and hemlock forests in British Columbia. It is therefore important to look for sustainably-forested wood, and the two main certification groups are FSCNonprofit organization that promotes forestry practices that are sustainable from environmental and social standpoints; FSC certification on a wood product is an indicator that the wood came from a well-managed forest. (Forest Stewardship Council(FSC) Nonprofit organization that promotes forestry practices that are sustainable from environmental and social standpoints; FSC certification on a wood product is an indicator that the wood came from a well-managed forest.) and SFI (Sustainable Forestry Initiative). FSCForest Stewardship Council. An independent, nonprofit organization that promotes responsible forest management through the use of a third-party certification process. FSC certification includes a chain-of-custody requirement that tracks sustainability of wood products from growth to end use. was created by environmental groups whereas SFI was originally backed by the wood products industry, and even though SFI has distanced itself from the logging industry, critics still say it is less rigorous than FSC.
Things get ugly between FSC and SFI when LEEDLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. gets factored in. LEED is the U.S. Green Building Council's rating system for buildings, and they currently give points only for FSC wood, not SFI. SFI representatives grumble that this is hurting the domestic lumber industry, but... well, if you're really interested you can read all about the "Wood Wars" at BuildingGreen.
You will now understand my next haiku:
Can't decide between
FSC and SFI?
Just build out of rocks.
Thermal bridges are a major avenue for heat loss in a building envelope. They occur when material crosses through the building envelope, creating a direct link between the heated interior and the cold outdoors and allowing heat to escape the building envelope. A classic thermal bridge is the shared concrete slab underneath a house and its attached patio; heat from inside the house travels outside through the concrete slab, and the furnace has to work harder to replace all the lost heat. You're basically paying to heat the outdoors. The reverse happens during the summer, when outdoor heat travels through the concrete into the air-conditioned house.
There are numerous ways to "break" a thermal bridge without losing the structural benefits of a shared platform, but many builders don't bother. Aqua Tower, a gorgeous new high-rise in Chicago, should have been built with special thermal breaks for cantilevered balconies, but the builders skipped that crucial step. The building is structurally sound, of course, but it's not nearly as efficient as it should have been.
I suppose I've already given away the punch line, but here's the next haiku:
Gently caressing the sky
Massive thermal bridge.
I already covered passive solar orientation in another blog post, so I'll skip straight to the haiku:
Squinting and roasting
As the western light shines in.
But look at the view!
The point here is that west-facing windows become a problem during the summer as the sun begins to set, filling the room with unwanted heat and glare. Sadly, most builders ignore passive solar principles when siting a house, instead placing windows toward the best view.
Of all the haikus I posted on Twitter, this one got the most retweets:
No one ever asked
When they built the Taj Mahal
“What about payback?”
Questions about payback are a common gripe among green builders. I ranted about it last year, but I'd like to add that conventional construction is often cheaper than green building because the costs have been externalized. For example, when we rely too much on carbon-heavy energy, we're shoving the costs onto the people who will be hit hardest by climate change. Or when we use materials with a toxic manufacturing process, we are saddling those workers and communities with the long-term cost.
Ted and I have not always made perfect decisions while building this house, but we sincerely tried to bear most of the cost burden ourselves. It made our house more expensive than I would have liked, but my only real regrets are the times when we cheaped out at someone else's expense.
Do you really need
That geothermal heat pump,
Or would caulk suffice?
A lot of people think the best way to improve their home's energy performance is to add fancy equipment like solar panels or a ground-source heat pumpHome heating and cooling system that relies on the mass of the earth as the heat source and heat sink. Temperatures underground are relatively constant. Using a ground-source heat pump, heat from fluid circulated through an underground loop is transferred to and/or from the home through a heat exchanger. The energy performance of ground-source heat pumps is usually better than that of air-source heat pumps; ground-source heat pumps also perform better over a wider range of above-ground temperatures.. But you can get a lot more bang for the buck simply by improving your thermal envelope. After that, go ahead and install some eco bling. You might not need that ground-source heat pump anymore, but if you install solar panels you'll be able to generate a much higher percentage of the energy you use.
If you want to build a Passive House, you first have to estimate the energy use in a ludicrously detailed spreadsheet called PHPP (Passive House Planning Package). PHPP is incredibly comprehensive and has to be filled out and tweaked by a highly-trained professional. But it lacks at least one key field:
Where do you input
“Milligrams of Valium”
Andrea Lemon lives in Brattleboro, Vermont. She and her husband Ted Lemon write the Almost Passive House blog.