Bourne Hill Council Offices
Viviene Sawyer, Senior Energy Officer, Wiltshire Council
Building type, sector and stage
Council Offices, post construction, in-use monitoring, South West, Salisbury
Grade II* Listed building refurbishment, curtain walling, green and brown roof, natural ventilation, thermal mass
Timing of this summary
Two years after completion (May 2010)
The building consists of a refurbished 18th Century Grade II* listed building (1973m2) and a new build rear extension (2630m2) which more than doubles the size of the council offices. The refurbished building houses offices and a registrar's office with ceremony room, whilst the new build extension houses offices with a flexible working approach allowing for 2 desk spaces provided for every 3 staff.
The new build extension is constructed of an exposed concrete frame, large areas of curtain walling, with green and brown roofs. External solar shading has been provided to prevent summertime overheating, whilst maximising the daylight entering the offices. The refurbishment of the existing building consisted of fabric repairs, re-roofing, changes to internal partitions, and upgrades to the mechanical and electrical systems.
The whole site is heated by communal gas boilers with ventilation and cooling predominantly provided by a natural ventilation strategy that makes use of the structures exposed thermal mass. Perimeter trench heaters provide heat into the new build office whilst hot water convectors provide heat in the existing building. The building has secure vents which can be opened at night by the BMS to allow for night time cooling of the thermal mass.
The integration of a heritage site with a new build extension will allow the project team to compare the energy use and occupant satisfaction of buildings from completely different periods but with the same use type.
The night cooling strategy, via secure BMS controlled vents is to be studied in detail in order that the team can understand how effective this ‘free' cooling strategy is.
A rainwater harvesting system supplies the toilets with clean rainwater. Lighting is predominantly controlled by daylight and PIR sensors.
The study has only recently begun and therefore initial findings are yet to be established.
Key Performance Indicators
Floor area: 2,630m2new build and 1,973m2 listed building
Building regs estimate of CO2: 21.1 kgCO2/m2.yr
EPC rating: B (50)
DEC rating: D (76)
Air tightness: 4.8 m3/hr/m2 @ 50Pa (new build)