Thermal image of window/wall junction thermal bridge

Retrofit of Colt timber bungalow

Main Contractor:

The bungalow (built in the 1960s) was found to have no insulation at all in any of the timber frame walls. The loft had only a thin layer of insulation, and the concrete floors had none. The oil-fired heating system was effective when on, but the heat disappeared quickly and the oil tank had needed refuelling 3 times in one heating season.

Summer overheating was also an issue, with a large south-facing area of roof and wall absorbing the sun’s heat and radiating it directly into the dwelling.

The retrofit strategy included insulating the external walls with hemp batts and woodfibre boards (as well as keeping heat in during the winter the insulation helps keep the heat out in summer, and the denser woodfibre boards provide thermal mass to buffer the sun’s heat and further help avoid overheating), along with thorough insulation of the ceilings, and insulation of all floors. A new heating system was installed, with heat provided by an air-source heat pump.

Services supplied:

  • Advice on low-carbon sustainable insulation materials and suppliers
  • Guidance on insulation strategy and techniques
  • U-value calculations
  • Recommendations for detailing to reduce thermal bridging and associated heat-loss
  • Practical on-site assistance