Results of Barratt's green house experiment

Volume house builder Barratt Developments has published preliminary findings from its experimental ‘eco village’ project in Chorley, Lancashire – a 15 month long test of how effectively ‘green’ technologies can be incorporated into new homes.

Dr Tony Sung, Chairman of CIBSE Electrical Services Group and Lecturer at the School of Mechanical, Aerospace and Civil Engineering at The University of Manchester has been monitoring the renewable technologies installed in the seven-unit development and are now compiling the report on their performance.

Ground source heat pumps and solar panels have come out best in the tests.

Sung said the ground source heat pump ‘worked very well’. On average a GSHP could generate 2.6 times the amount of energy it consumed. At these performance levels, an £7,800 GSHP would reduce CO2 emissions by 62 per cent and would take around 15 years or less to pay for itself at today’s electricity prices using a simple payback method of analysis.

Photovoltaic (PV) roof panels also ‘worked very well’. On average, an unobstructed PV system generated 850kWh of electricity a year. At these performance levels, with a net-metering arrangement and a Renewable Obligation Certificates income, a £4,500 PV system would take around 37.5 years or more to pay for itself at today’s electricity prices.

Solar hot water thermal panels were declared ‘reasonably satisfactory’. On average, a 2.5 sq m or higher unit could heat a 180 litres tank of hot water on a cloudless day. The simple payback period will depend on the hot water demand of the household and this work is still progressing.

However, wind turbines were judged ‘disappointing’. Both the 1.7m and 1m turbine performed below the theoretical available output based on the recorded wind speed throughout the trial period. Simple payback period analysis has not been carried out.

Micro-combined Heat & Power units have been ‘trouble free’. On average, the electricity to heat generation ratio of the units was around five per cent. The technology is still under trial and further results will be published at a later date.

Dr Sung examined how much each technology cost to install, what exactly it can and cannot do, what combinations work best, what they will save in terms of carbon emissions and whether householders could expect to make any cost savings as a result of living with them.

Mark Clare, CEO of Barratt Developments, said: “The eco village has been an invaluable test bed which has helped separate renewable myth from renewable reality. The challenge now is to drive down costs to ensure that they have the widest possible take-up.”

“We are now using renewable technologies at 40 of our developments. The Photovoltaic roof panels and Solar Hot Water Thermal Collectors are key features which we will use going forward. So too is the Air Source Heat Pump, which operates on similar principles to other Heat Pumps.”

The experimental prototype technologies have now been removed from the Chorley showhouses, which will be sold to members of the general public. More research on the low carbon technologies used at the eco village will continue at The University of Manchester by the Built Environment Research Group for a further two years.