July 06, 2006

Recycling Buildings For a Carbon Neutral Future

Recycling Buildings For a Carbon Neutral Future

Event type: Conference

Date: 2006-06-22

Rating: 5 out of 5

During Architecture Week we went along to AC Architects here in Cambridge to find out how they've taken an old shop and turned it into their offices, and incorporating all sorts of environmentally-friendly techniques along the way.

Their aim was to produce a building which is carbon-neutral as well as being a nice place to work and live (there are a few flats above the offices, which they'll be renting out), and I think they've hit the target. The event, or achitour as it was billed, consisted of a short presentation outlining their approach and covering some of the technology and workings that went into the building, followed by a tour of the site. It was a very open and friendly affair, and the architects were obviously passionate and proud of what they are doing.

Keeping Things Cool

Given our recent heatwave, I've been wishing that we had something similar to their passive stack ventilation system. Rather than installing air-conditioning, there is a carefully designed network of airways through the building. Air is drawn in through the basement from a huge air-duct (pictured right).

It then flows under the flooring and into the rooms through grates in the floor (below left). "Indoor windows" (below centre) allow the air out of each room to be ducted up to the vent on the roof (below right, the ventilation stack is "chimney" on the right). The natural chimney effect means there's no need for fans and the amount of air being drawn through each room can be regulated by opening or closing the "indoor windows". The system was working well when we visited, and the main problem they've had so far is keeping the under-floor air-flows clear - the big open spaces are too tempting to plumbers and electricians looking for somewhere to route services out of sight.

There are a couple of other techniques to help keep the building cool in summer: the bare brick interior walls act as a heatsink during the day, taking in heat and then releasing it at night; and there are shutters on the windows to let you reduce the amount of solar energy entering through the windows. Plus the shutters are lockable, so you can leave the windows open to allow ventilation without compromising the security of the building.

Warming Up

Obviously, in addition to keeping things cool, you need a way to warm things up - the entire building in the winter, and even just water for the showers, washing machine, etc. in the summer. The heat for the hot water and the underfloor heating all comes from the heat store (pictured left), basically a large hot-water tank in the basement which can be heated through a number of different means.

If the sun is out, then solar water panels should provide virtually all the heat required and even in the winter will supply a reasonable amount of heat. The fall-back solution involves four thirty metre deep boreholes drilled in the garden behind the building and an appliance called a heat pump. The heat pump (shown right) is about the same size as a washing machine and uses similar techniques to a fridge, but in reverse, to extract and concentrate heat. An anti-freeze solution is pumped through the boreholes and the heat pump - when it leaves the heat pump (having had all the heat sucked out of it) it's very cold, the boreholes use the fact that the surrounding earth remains at a pretty constant temperature to "heat" the anti-freeze back up to around 10°ree;C. The heat pump can concentrate this low-grade heat into something more useful.

Finally, if worst comes to worst, there's an immersion heater in the heat store, but that's mainly as a back-up if the heat pump breaks and the sun isn't out.

And There's More...

The ventilation and heating systems are just the big headline grabbing items in the build. There's a raft of other measures to help the building reduce its environmental footprint even more: rainwater is collected in a huge tank buried in the garden and used to flush toilets and as softened water for the washing machines; throughout the building there's super-efficient insulation; there are a few photo-voltaic solar panels to provide some electricity; and the remaining electricity comes from a green provider.

The whole project has been undertaken with an eye on the sustainability of materials used. A lot of the material removed when preparing the site was taken to be recycled, although they pointed out that it would have been harder to achieve if they hadn't done a lot of the preparation work themselves. There are reclaimed materials used in all sorts of places, and in the case of the wooden floors and vents they often look better as well as being greener. And thinking of the future has influenced the construction - the insulation material can be recycled when it's no longer needed, and the brickwork uses lime mortar as that will let the bricks be reclaimed intact if it's demolished so they can be reused.

It was an interesting look at some of the techniques available to make better buildings, and if you missed it you could still be in luck - as the original event was so popular, they are running it again on Tuesday 5th September 2006 from 6.30pm until 8.30pm. Once again they will be charging £5 for refreshments with any surplus going to East Anglia Childrens Hospices, and again there will only be 25 places so booking is essential.

  • Tags: architecture cambridge green carbon_neutral architecture_week

    Posted by Adrian at July 6, 2006 02:50 PM | TrackBack

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