Baseload, Bioenergy, Energy Efficiency

CHP an Ideal Fit for ‘World’s Most Environmentally Friendly’ Building in UK

The Co-operative’s new headquarters at One Angel Square in Manchester, UK was lauded last month during its official opening for meriting the title, ‘World’s most environmentally friendly building.’

Combined heat and power (CHP) technology is at the heart of the structure.

COSPP online spoke to Dennis Wheatley, Senior M&E Manager at BAM Construction, and he outlined how cogeneration technology proved the right fit for the Co-op’s lofty energy-efficient ambitions.

“When we took on board the design and build contract that was prepared by the client, from day one there was a requirement to provide a design that would achieve a BREEAM (BRE Environmental Assessment Method) score outstanding rating and a DEC (Display Energy Certificate) analysis of A.”

The original design had a provision for a biomass boiler but it was decided to change that through a two stage tendering process. Through this process BAM developed a design with the client and also took on board a major advantage the Co-op holds, in terms of its power potential; its land.

“It was decided, after modelling and predictive technology was deployed, that from the point of view of energy usage a DEC A grading couldn’t be achieved by any other means than by a CHP.

Once we were engaged into the process the client decided to change his business farming practices so that he could produce a low-carbon factor energy efficient fuel from his rapeseed crop.”

The decision meant that the CHP units at Angel Square are driven by pure plant oil or rapeseed oil, which was ideal for the Co-op as they grow their own crop. This is enabled as in the fallow periods of their rotational crop they have allocated a period of time to growing rapeseed with highly desirable results for the state-of-the-art building.

“The client has about 70,000 acres of it throughout the UK. It’s a massive fuel resource,” continues Wheatley. “They could have bought this fuel in on the commercial market but happens to have it himself. They are then engaged with another company that cold presses it under a strictly controlled refining regime. This fuel oil is very rigidly monitored by Ofgem rules as they pick the specification requirements of the fuel so that it is certified for Renewable Obligation Certificates.

One Angel Square has up to 6000 litres of rapeseed biofuel on site at any one time. It was that use of CHP that enabled the development to achieve the highest recorded BREEAM, quite an achievement when you think that 250,000 buildings have been certified by this method worldwide up to this point.

Along with the judicious use of CHP there are lots of other energy saving features built into the design that helped it achieve such recognition, including regenerative motors in all the lifts pumping back into the system, extensively complex heating and lighting control systems, underground earth supply ducts that use subterranean concrete to heat and cool the building, and a thermal jacket around the façade of the building which retains heat. In addition Its computer systems recycle waste heat.

BAM frequently uses cogeneration in its buildings as and when it is deemed the most appropriate fit and Wheatley says getting that element right is essential.

“It all depends on the building design. Some clients are eager to go down the CHP route but don’t properly select the CHP unit to suit the design of the building. It needs to be at the heart of the design and you need to take into account for example that absorption chillers match physically to the CHP plant.”

“There is also a number crunching exercise involved; if you are running a building 80 or 90 percent of the time on fuel oil or gas, you may have to replace those engines every three to four years, and build that into the overall building running costs.”

“Ultimately the client will decide based on costs and benefits. The Co-op is a master of its destiny, in terms of fuel source, and had more of a safer future assessment in terms of costs, except perhaps if it comes to bad weather conditions during summer.”