Pennyland project

The Pennyland project was a scientifically controlled experiment on an estate of 177 houses in the Pennyland district of Milton Keynes, Buckinghamshire, United Kingdom, to compare UK and Danish building energy efficiency standards.

Although identical externally, half the houses were built to the then Building Regulations energy efficiency standards, the other half to the much more demanding 1977 Danish "BR77" standard. In Europe, BR77 and the Swedish "SBN-80" standards set the benchmark for low-energy housing at the time.

Sponsored by the Milton Keynes Development Corporation, and with the technical expertise of the Open University Energy Research Group, the project was initiated in 1976 and constructed during 1979 and 1980.

Design

The estate was laid out to take advantage of solar gain, and were designed with a cavity wall with a poured concrete inner leaf to provide thermal mass and increase airtightness. Changes made to meet the Danish standard included:
*Glassfibre roof insulation increased in thickness from 80 to 150mm (improving the U-value from 0.5 to 0.41 W/m2K)
*Glassfibre cavity wall insulation increased from 50 to 100mm (0.6 to 0.34 W/m2K)
*Ground floor perimeter insulated installed (0.45-0.76 to 0.34-0.56 W/m2K)
*Draft-proofed double glazing instead of single glazing (4.3 to 2.5 W/m2K)
*Airtightness measures (cutting overall air infiltration to around 25% of the UK average).

The designs also incorporated draft lobbies, partial central heating, mostly using very low water content gas-fired boilers with additional control measures (but a few with gas-fired warm air heating).

For comparison, two additional groups of control houses were built on an adjoining site at Neath Hill

Lessons learned

Among the lessons learned were:
*Interlocking the operation of the gas boilers to when the central heating pumps were running lead to an unexpected 20% fuel saving.
*The effectiveness of the wall insulation was less at corners and window heads due to installation difficulties, requiring better detailing and operative training in future projects.
*Mould growth in over half the properties, attributed to the high levels of airtightness, led to the strong recommendation that mechanical heat recovery ventilation should be incorporated in future low-energy projects.
*The floor edge insulation failed to achieve the predicted heat loss reduction.
*The solar gains were frequently less than expected due to residents using net curtains, or growing plants, to prevent by-passers seeing through the large windows.

Impact

Measurement of the energy usage showed that the Pennyland houses used, on average, 50% less energy than the then UK average of 280 kWh/m²a [http://www.aecb.net/PDFs/EST.pdf] .

A cost-benefit analysis of the project showed that the cost of the additional energy efficiency measures would be recovered within four years, leading to a call for such measures to become compulsory.

The Pennyland project was one of a series of low-energy building experiments that took place in Milton Keynes, initially sparked by the 1973 oil crisis, including the Linford low energy houses and the major Energy World demonstration project and exhibition.

ee also

*Energy World
*Energy efficiency in British housing
*Energy use and conservation in the United Kingdom

*Sustainable development
*Energy conservation
*Passivhaus low-energy building standard
*

External links

* [http://www.ens.dk/graphics/Energi_i_tal_og_kort/statistik/indikatorer/DanishReport2004.pdf Energy efficiency in Danish housing]
* [http://www.lmu.ac.uk/as/cebe/projects/york/york_final.pdf York Energy Demonstration Project]

References

*"The Pennyland project report", J Chapman, R Lowe & R Everett; Open University Energy Research Group, ERG 053/ETSU-S-1046
*"Social survey – Pennyland residents; S Meikle; Milton Keynes Development Corporation