Sustainable housing in action
What's being done NOW to build environmentally sympathetic homes? In a number of countries, proposals that, from 2016, new buildings should be sustainable have been watered down or scrapped. But one development in Cambridge is sticking to the principle anyway. Emma Sackville went - on site - to speak to construction director Gavin Heaphy...
Gavin - We are recycling water. We are generating our own electricity and heat through our energy centre which centralises the production of electricity and hot water across the whole of the development for all 3,000 homes. We are generating electricity through photovoltaic cells, but what we're also doing to achieve that is ensuring we reduce our carbon footprint both in the construction of the homes but also in the materials and also in the performance of the homes when they're in full use.
Emma - And we've got this energy centre behind us - is that right? So it's a sort of tall, grey building - how's it going to function?
Gavin - So, within that building there are different ways of both generating electricity and heat. In the initial phases where the whole project is very much heat lead, so we've got more demand on heat rather than the electricity, we use boilers. So the centralised boilers pump hot water around the development and then, as the development requires more in the way of electricity, we'll start generating electricity with engines.
Emma - This system is known as combined heat and power, or CHP, and by centralising the boilers, not only do they make it more efficient over the whole site, they can also use the waste heat from the engines to power the boilers. And Gavin reckons it can add up to an overall energy saving of up to 40%.
Building on this kind of level is quite a big ask. What have been your main challenges and stumbling blocks when you've been trying to achieve it?
Gavin - The main stumbling blocks have been to do with finding the best people to deliver these projects. Not everybody has done anything on this scale before, so finding the right resources both in terms of the management team, but also the contractors and their sub-contractors as well and, also, making sure we keep a close eye on how that performance is working on site.
Emma - And, obviously, there's higher costs associated with building something sustainably. How are you balancing off the cost with the trade off of making sustainable housing?
Gavin - Well, ultimately, if it's sustainable it also means it's also going to be more cost effective to run during it's operational phase, so we're actually making an early investment in sustainable development to ensure that what we have to manage for the next 50 to 100 years on this development is, actually, more cost effective in the long run, so lower energy bill, less maintenance if you like, and so on. It will reap the benefits in the long term.
Emma - Oh, I've lost my hat! Once I'd retrieved my hat, I wanted to find out a little bit more about their water recycling plans. Water management and recycling are the major consideration when planning sustainable housing because, at the moment, we use completely clean, drinkable water and, essentially, flush it down the toilet. There's an option to recycle so called grey water, which is any used water that hasn't been down the loo with all the associated extras. We could use this for things like flushing the toilet, or watering plants, basically, anywhere that we don't need to drink it. We headed over to the water management part of the development for Gavin to tell me a little bit more about what they were doing on this site...
So, at the moment, we're here by this very lovely, surprisingly lovely, lake actually. What's the lake doing here - what's it part of on this site?
Gavin - The lake's part of our water recycling system but also has other uses as well. If you like, the whole water attenuation and recycling system we have across the site has many purposes. The lake actually retains water on the site so, as you can imagine, a site of 150 hectares has an awful lot of water falling on it when it rains and we need to deal with all that water. So, what we've done by attenuating the water on the site we are alleviating flood risk, that water gets recycling and there are two water networks across the whole of our site. A normal potable water network you get from your supplier, say Cambridge Water from this area, and there is a second network that is used for irrigation, for toilet flushing, and also now for washing machines as well.
Emma - So you've got two different kinds of water going on?
Gavin - Yes. I think water recycling has been around for many years, hundreds of years, but what we're doing here is doing it collectively if you like. The whole system is feeding the whole site so you're not reliant on individuals collecting the water themselves. This is being done centrally and it's the first time it's been done at this sort of scale. The lake also provides amenities both for the public people and, as you've just said, you quite like the look of the lake, it's a very nice place to be. Hopefully when the sun's out a bit later in the year it'll be even nicer but, on top of that, it also creates habitat for wildlife too.
Emma - And speaking of wildlife, one of the things I found really surprising on this site was the commitment to ensuring the impact on the local environment was newt-ral.
Gavin - So, throughout the delivery of the project we've had to look after Great-crested newts. In the area immediately in front of us here there's a large pond just beyond those bushes there. The small green fences you see are how we control the movement of the newts to ensure they don't get out into the wider site and get squashed - putting it bluntly - and we're standing at the moment right on top of our newt tunnel. This tunnel is of a reasonable size and will allow the little gems to migrate between the ponds and make sure they don't get hurt in that process.