BedZED – solar atrium elevation

BedZed sits like an island in the south London suburb of Beddington (BedZED stands for Beddington Zero Energy Development).  The day I visited it, I did the long walk from the local train station, along a fairly busy, not very attractive arterial.  Suddenly, there it was – a sort of Earthbound naturalistic UFO set amidst the dreary backdrop of run of the mill flats and commercial buildings.

BedZED is mixed housing/office development, with about 100 townhome units and about 13,000 square feet of offices.  But that benign, run of the mill description doesn’t really give you any sense of it.  My visit to BedZED is perhaps the single most hopeful day in my life, environmentally speaking (except for my visit to Hockerton – more on that later).  BedZED is one of a handful of buildings planet-wide that has what is at least close to a truly sustainable footprint.  Like zHome, BedZED established a number of environmental benchmarks, shown below, along with how well they’ve actually performed (the community was completed in 2002). What BedZED shows us is that radically more sustainable buildings are possible, and within reach now, not some indeterminate time in the future.  Here is a chart of the environmental specifications for the project, along with how it’s actually performed:

The energy component of BedZED is what I think is most compelling, and I am really taken with the technologies they used.  What is most interesting to me is that many of them are completely different from zHome, even though the climates are quite similar.  This gives me a lot of hope because it says there are a lot of technological pathways to achieve zero net energy/carbon buildings.

BedZED starts with the same hyper-insulated wall section that zHome does – that seems like a basic constant in our climate.  But BedZED uses masonry (brick and concrete) walls – typical of European residential construction – rather than wood stick frame.  BedZED has also wholeheartedly embraced passive solar heating of the homes, with a solar atrium sitting on the south side of the homes, unlike zHome.  This solar atrium has glass with a high solar heat gain character, allowing it to heat up dramatically. Once this atrium has warmed up toward the end of the day, the residents open an inner set of highly insulated triple paned French doors to allow the heat into the units. This solar heating provides the majority of the required heating for the units. Hot water, and supplemental water based hydronic heating, is provided by means of a combined heat and power unit for the whole project. This is essentially a large boiler with a turbine attached to generate electricity. This system was designed to run off wood waste, but when I was there it was running off of natural gas. The passive solar heating system heats the homes well enough to only need one heating element in the homes: a heated towel rack!

Combined heat and power building

Where are your priorities? Heated towel bar

My favorite view of BedZED is across the soccer pitch, with BedZED, and a neighboring project which was built at the same time, in view next to each other. The BedZED architects (Bill Dunster Architects) nicknamed the neighbor BedHED, for Beddington High Energy Development. It’s a pretty amazing image – two projects, built at the same time, with the same essential building structure and technology, but one which uses radically less resource and emits radically less CO2. Smart, thoughtful design, coupled with innovative technologies got them there – Yes they did – and Yes we can! (Forgive me, I couldn’t help myself, it’s Inauguration Day tomorrow).

BedZED and BedHED

Here is a link to the official BedZED website.

zHome is being built in accordance with stringent environmental benchmarks.  These are actually contractually established between the City of Issaquah and Howland Homes.  You can  read the benchmarks here if you would like to delve into these further (all 14 pages of them!).  You can see for yourself exactly what design criteria have been established for the project.   

So why benchmarks?  To me it goes back to the graph shown on the Why Green Homes? portion of the site.  In big picture terms, zHome is about looking at the cold hard numbers of building’s hefty environmental impacts, and taking those numbers as close to zero as possible.  There is something pure about a numeric driven design process:  set your goal, and let the design process figure out the most efficient way to get there.  It’s not that dissimilar to a gas or carbon tax – get aggressive, and then get out of the way and let the people involved figure out how to respond.  I also think there is something powerful about giving a number to what you’ve achieved, as opposed to some more qualitative measure – I think your average person can get it better.

And then there’s accountability and integrity.  The zHome benchmarks are all subject to verification by the City.  In some cases our other partners are involved in this process as well.  For example, Howland Homes’ energy model (done by Stantec) has been vetted and reviewed both by the City and the WSU Energy Program.  We feel that if you’re going to make strong claims (such as the project is achieving zero net energy), there should be integrity and transparency behind those claims.  Very few of the projects that are claiming zero net energy have actually undergone energy modeling to verify the claim, and fewer still have been verified by outside parties.  And many projects and builders that use the term “zero energy” are actually talking about it conceptually, in terms of it simply being a goal or good idea, or being part of a long term program to achieve zero net energy sometime in the future.  I feel that that dilutes the power of the name because it implies this very difficult goal is being met regularly.  Certainly our goal should be zero energy, but when it comes to individual projects, zero energy terminology should be used carefully and transparently.