Sustainability. The New Black

 

June 2006

Andrew Mellor

Certainly, the issues of climate change, water supply, energy production and pollution have never been higher on the political agenda. Politicians from all sides are jumping on the bandwagon and preaching ‘green’ whether their parties are blue, red or yellow; in fashion terms, sustainability is definitely the new black.

The knock on effect this has had on the construction industry has been a raft of new legislation and standards designed to improve the energy efficiency and environmental quality of our built environment. EcoHomes 2006 includes credits for renewable energy; Part L 2006 aims to achieve 20% reduction in carbon emissions over 2002 standards; the GLA and some local authorities now require 10% renewable energy provision; the proposed Code for Sustainable Homes (unlikely to be mandatory for private housing) will probably have minimum energy levels set above Part L. In our view, we welcome these long overdue and enhanced requirements, however taking a sensible approach to sustainable design - by initially reducing energy consumption and heat loss through utilising passive design techniques and super insulation levels - can help reduce the quantity and therefore the cost of renewables required to fulfil a 10% planning obligation.

Understanding renewables

Thanks to certain leading politicians, everyone knows what a wind turbine is and how they can be a source of renewable energy. However, simply bolting on renewable energy technologies requires additional capital costs and the truth is, pay back times can be long at today’s energy prices.

So are we saying renewable technologies are a waste of time and money? No, not at all.

Sustainable design should be approached as ‘sensible’ design – if you have to add renewables as part of a statutory 10% provision, reducing energy consumption of the dwellings through good passive design and incorporating an enhanced thermal envelope will help to reduce the amount of renewables required.

Sustainable design in practice

As architects, one of the first things we consider when designing any building is to study its orientation and maximise the opportunities for using solar gain. Utilising passive solar design techniques can reduce heating requirements (and therefore CO2 emissions). It is also important to consider solar control methods to prevent overheating and reduce the future requirement for air conditioning.

This however does need to be taken into account alongside thermal insulation levels. An air tight envelope helps prevent uncontrolled air infiltration and heat loss, further increasing the energy efficiency.

We recently visited the German city of Freiburg which prides itself on being the ‘solar city’ of Europe. In the Solarsiedlung (solar community) area of Schlierberg, 58 timber-framed houses have been constructed using off-site methods to formidable thermal standards. East-west aligned, with 400mm of insulation in exterior walls and a woodchip-fired Combined Heat & Power (CHP) plant; heating requirements are a tenth of a traditional house. Indeed, those homes which also have photovoltaics actually produce more energy than they use and are able to sell the surplus energy to the national grid at a profit.

At the St Matthew’s estate in Brixton, PRP designed a block of keyworker flats which utilises super insulation levels, passive solar design techniques and heat recovery to ensure space heating requirements are negligible. This means very small heating bills for residents. In summer, a combination of natural ventilation and thermal mass keep the apartments cool. Water heating to the flats is provided by solar panels supplemented by a wood pellet burning boiler. The boiler only needs to be restocked with wood pellets every 10 months.

Similar to the energy labelling on white goods, the Energy Performance of Building Directive requires all dwellings to have a certificate stating its energy performance. In St Matthew’s, residents’ energy bills are expected to be less than £75 per year, a strong selling point for the developers. In eco-conscious Germany, a high proportion of Freiburg’s inhabitants are also happy to pay the 5% extra it might cost to build a new, sustainable home for the payback in terms of lower energy bills, social and health benefits. This is beginning to be echoed in the UK, where purchasers are willing to pay a premium knowing that in the future the outlay is likely to be repaid as energy costs soar.

New legislation embraced by enthusiastic developers will create more energy efficient homes. Couple that with environmentally aware purchasers who are able to make their housing choices based on accurate product knowledge and we could begin to make real progress in reducing the environmental impact of new homes on our planet; let’s hope it’s a trend that stays in fashion for many years to come.