Responsibilities on project: Lead Architect
Duration on site: 11 Months including music practice room
Site completion: September 2014
Gross floor area: 258m2
Build Rate: £1,677.84m2
U Values: Roof – 0.16 w/m2k, Walls – 0.18 w/m2k and floor 0.16 w/m2k
Originally built as a purpose designed ‘school for lady gardeners’ in the early Twentieth Century, Ragged Lands was purchased by our clients who engaged BBM to devise a strategy for carrying out a thorough ‘eco-retrofit’ of the 258m2house. As detailed elsewhere on our website, the project also included for a purpose-built music practice room which was created in the extensive gardens.
To assist BBM with the energy efficiency appraisal, energy and building services consultants, Robinson Associates were brought onboard to calculate the existing energy profile of the house and to benchmark a ‘shopping list’ of energy efficiency upgrades. The baseline annual energy requirements and carbon emissions for the house were derived from SAP 2009 predictive calculations and IES thermal modeling. For space heating alone the existing house was found to have a carbon emission rate of around 84 kg/m2/year or 198kWh/m2/year and for such a large house heated using a propane fired gas boiler, this meant the energy costs for space heating in particular were extremely high. After a carbon versus cost benefit analysis was carried out using the various roof, wall, floor and glazing proposals had been evaluated, the report concluded the house could be realistically refurbished to achieve a carbon emission rate of around 20 kg/m2/year or 41kWh/m2/year in space heating demand.
The strategy also included use of solar thermal water heating panels mounted on the roof and a 4kWp photovoltaic (solar electric) array mounted on the roof of the new build music practice room located about 30 metres to the west of the house.
The house itself was actually insulated on the outside, meaning some of the roof verges and eaves needing to be modified. A combination of render and brick slips was used. In a small area of ventilated clay tiles on timber stud walls, it was possible to insulate from the inside. New glazing was supplied throughout and the opportunity was taken to refurbish the clay tile roof – works which required a formal bat license to arranged and all planned and set prior to the contract being let.
The result is a house which completely resembles the old one in its material palette but is now far more energy efficient and more durable than before. Internally the ground floor which was part suspended timber floor and part ground bearing slab was given two highly capable energy efficiency upgrades to suit. Extensive new internal fittings, bathrooms and kitchen.