Sustainable architecture encompasses the energy a building uses, as well as the materials used. Any reduction in Greenhouse Gas emissions required to product a building will contribute to the global effort to fight climate change, immediately. This is the idea of doing things efficiently: accomplishing the same task with less energy allows us to either store, or do other things with that saved energy.
Lately we’ve been looking into the Green House Gas implications of certain types of insulation for buildings. The main driver in GHG for insulation is the blowing agent that is used the make the foam. It is unclear at the moment the rate at which this leaks (off-gasses) from the finished product.
The impact that the production of insulation is measured by Global Warming Potential (GWP). Aaccording to BuildingGreen: “Global Warming Potential is a measure of how much heat is trapped by a given mass of gas, contributing to global warming, compared with the same mass of carbon dioxide. Carbon dioxide has a GWP value of 1″. Alex Wilson, from BuildingGreen have conducted research in to the impact of various types of insulation. See below for a table showing various types of insulation and at the far right side, the Lifetime GWP to compare the energy impact of the material.
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Looking at the data there is some interesting results:
- – Mineral wool and SPF – closed-cell (water-blown) foam have almost equal lifetime warming potential. They also have a high payback in years the more inches of insulation you add.
- – Spray polyurethane foam (SPF) – closed-cell (HFC-blown) and Extruded polystyrene (EPS) have far and away the highest warming potential.
- – Cellulose dense-pack has the least Global Warming Potential. Cellulose is made from plant fiber. Cellulose also has the quickest payback at far and away the highest possible insulation. Indeed, judging from the chart above, you could achieve R-100+ in walls with a 1 year payback on the investment.
- – Fiberglass Batt insulation has the second least warming potential.
It is worth keeping in mind that if the overall goal is sustainability, design decisions which minimize long-term energy costs (such as air tightness, insulation, and continuity) will have a larger influence on a buildings Global Warming Potential. The UN Inter-governmental Panel on Climate Change says:
“For typical standards of building construction, the embodied energy is equivalent to only a few years of operating energy, although there are cases in which the embodied energy can be much higher (Lippke et al., 2004). Thus, over a 50-year time span, reducing the operating energy is normally more important than reducing the embodied energy. However, for traditional buildings in developing countries, the embodied energy can be large compared to the operating energy, as the latter is quite low. “
A balance must be struck between the energy used to produce the building, the unique design considerations of the project, site, client, and the energy used to run the building.
Check out the full article here: http://www2.buildinggreen.com/blogs/avoiding-global-warming-impact-insulation
