Achieve Code Level 4 with ICF Construction

Client: Rochdale Borough Wide Housing
Contractor: Jackson Jackson & Sons Ltd
Architect: Pozzoni LLP
Completed: May 2011

HOUSING – DOVER STREET, ROCHDALE

This development of 6 no semi-detached bungalows for the elderly has been constructed on a former, disused, playground classed as having low ecological value.

The dwellings were constructed using Insulated Concrete Formwork (ICF) to minimise heat loss through the building fabric, and increase air tightness levels. This modern method of construction achieves extremely low u values and, in combination with solar hot water panels, achieves 44% reduction in carbon emissions. The system build also creates a simple trail for responsible sourcing certification meaning more credits are awarded in the MAT 2 and 3 sections of the Code assessment.

Mechanical ventilation with heat recovery is provided to ensure internal comfort and maintain air tightness levels. The fan uses very little energy to refresh the air supply in the dwelling and extract heat from the exhaust air in the kitchen and bathroom, with optimum efficiency. The sanitary ware and rainwater harvesting system, which feeds the WCs, achieve 4 credits for reducing the water use, as well as the surface water run-off, on site.

All rooms have a view of sky and residents have access to a private garden with cycle storage and recycling facilities. The properties have been sound and air tested and maximum credits are awarded in both sections, with a sound insulation performance exceeding Building Regulations by 9dB.

Technical Details:

Ground Floor 0.11W/m2K:
65mm screed on 175mm insulation laid on in 125mm situ concrete floor on polyethylene DPM on 50mm blinded virgin aggregate sub-base.

External Walls 0.11W/m2K:
Render on ICF consisting of 2 sheets of 75mm expanded polystyrene joined with light steel studs, infilled with 100mm in situ concrete with 75mm rigid insulation board internally, plasterboard and paint finish.

Roof 0.10W/m2K:
400mm mineral wool insulation along the joists at ceiling level.

Windows 1.40W/m2K:
Double Glazed uPVC windows, AAA Rated.

y Value 0.04W/m2K:
This thermal bridging value results from the use of Enhanced Construction Details which minimise air leakage.

Air Permeability 4m3/h/m2:
The design air permeability rate of 4m3/h/m2 was significantly exceeded with 2.83 and 2.97 m3/h/m2 achieved in the two properties tested.

Heat Loss Parameter:
0.93 – 0.97W/mk

Space Heating & Hot Water:
Vaillant Ecotec Plus 612 condensing gas boiler with time and temperature zone control AND load compensator.

MVHR:
Nuaire MRXBOX 95 (loft) 0.69W/l/s Specific Fan Power and 92% Heat Recovery efficiency.

Low and Zero Carbon Technology:
200 litre hot water cylinder with 97 litres combined solar storage connected to 3 no Schuco flat plate collectors on 30 degree pitched roof, East/West orientation.

Surface Water Run Off 53.4m2 more volume post development:
Rainwater harvesting tank sized to collect water for use in the WCs and for ground irrigation. Attenuation tanks reduce the remaining surface water run-off to 5 litres per second.

Conclusion:
The excellent u-values and air tightness levels resulting from the ICF
construction enable Code Level 4 to be achieved with relative ease and minimal ‘bolt-ons’. This ’passive’ approach reduces maintenance and is essentially ‘fit and forget’.