**5.1. Construction**

The measures used in the refurbishment of the block incorporate specific approaches to de‐ sign and specification to reduce the on-going environmental impact of the building and to improve the living conditions of the potential residents. Working within the constraints (both physical and statutory) of the existing blonde ashlar and random rubble sandstone fa‐ çade and structural cores, a new internal layout was constructed to provide flatted accom‐ modation. The new insertions within this masonry skin are generally lightweight timber construction. Figure 9 shows the general flat arrangement.

**Figure 9.** Typical Plan Gilmore Close

The thermal performance of the building was improved by bringing the fabric up to contem‐ porary standards through a process of internal dry lining and insulation to achieve a U-val‐ ue of 0.25W/m2 K.The thermal performance of the historic timber sash and case windows was also improved through the use of secondary internal glazing improving U-values to 1.8W/m2 K. Both of the above strategies adhered to the design principles dictated by the building's historic status in that they did not materially affect the principal elevation. To the rear a south facing, semi-glazed (approx. 50%) sunspace with an average U-value of circa 1.0W/m2 K has also been incorporated into 12 of the dwellings to provide additional amenity and to make use of passive solar gains.

The principle active technology employed throughout the development is a vertical ground source heat pump (GSHP), which, along with an electric back up heater, provides for the hot water and space heating demands of the full building. Delivery of the space heating is through a wet under-floor heating system. Due to limitations of the timber intermediate floor structure this is provided within proprietary insulated trays rather then being con‐ tained in a screed.

Ventilation of 13 of the dwellings also allows for the use of heat recovery through propriet‐ ary mechanical ventilation with heat recovery (MVHR) units. In the 1 bedroom apartments (without sun spaces) a conventional system of opening windows, background trickle venti‐ lators and mechanical extraction from wet spaces has been installed. Elsewhere a whole house MVHR system draws air from the kitchens, bathrooms and sunspaces, and after re‐ covering waste heat, delivers fresh warmed air to the hall spaces, with the intention that this will dissipate to adjacent spaces. Note that MVHR relates to an energy strategy but is viewed primarily as a ventilation aspect with the heat recovery aspect being secondary.
