Underground success

Some of our best work happens 150 metres underground

Over half the energy used by most buildings goes into heating and cooling. We should know. As the developer and manager of millions of square feet of commercial property throughout London, we're always on the look-out for new ways to maximise energy efficiency. One of the most significant trends in recent years has been the increasing sophistication of large-scale geothermal heating systems.

As a technology, geothermal heating isn't exactly new – the Romans used it to heat many of their baths. It involves drilling boreholes into the earth, pumping water through pipes and using the difference in surface and subterranean temperatures as a source of energy. A system of heat exchangers allows you to heat buildings in winter and, with a flick of a switch, cool them in summer. It takes a significant strain off air-conditioning requirements and makes for a low-maintenance, environmentally-friendly solution in the long term. But it does involve an initial outlay and a serious engineering challenge, especially when you're dealing not just with a single home, but a commercial and retail development covering 50,740 square metres.

That's exactly the case with One New Change|, a spectacular new development on a sensitive site next to St Paul's Cathedral. Our engineering team has drilled to a depth of 150 metres to install a ground source energy system involving 219 closed loop energy piles and two open loop bore holes – the largest commercial application of borehole technology in Europe. In the process, we've drawn on lessons learned from a previous redevelopment at Eastbourne Terrace|. That gave us insight into some of the unexpected challenges that can crop up – you never really know how much groundwater is down there until you start drilling, and both ground and water temperatures can change over time.

Owning and managing such a large portfolio throughout London affords us the privilege of being able to try out new methods and carry the lessons forward into successive projects. But we also consider it a responsibility. Our market position requires us to be a pioneer in sustainable ways of working, whether it's green roofs, rainwater recycling, solar control glazing, photovoltaic panels, or recycling waste. We begin each new project with a commitment to achieve a minimum 'Very Good' BREEAM assessment and come in at least 20% below the current Building Regulation requirements for CO2 emissions. It's about meeting government targets and going further wherever possible – even if that means 150 metres below the ground.

"During 2007/2008, we met our commitment to design commercial buildings with, on average, 20% lower carbon emissions than required by building regulations. We actually achieved a 35% improvement. We're now on target to reach our 2010 goal of a 10% reduction in CO2 emissions in our managed offices." Dave Farebrother, Environmental Director