LARKRISE
A low-energy Design and Build in Stroud
"The Greenheart team take real pride in their work which makes it a more enjoyable process for everyone. They are respectful and have integrity and this is extremely important to me when making such a significant investment. I liked the fact I could have a significant input into the design. Working with the team on the design meant the process was more efficient as they understand every detail of the construction and can provide an idea of costs throughout..."
The client came to us having purchased a bungalow for its spectacular location, with extensive views towards the Bristol channel. Unsure whether a thorough remodel/retrofit, or a knock down and re-build was the best way to go, we set about sketching out some concept ideas and comparing the potential outcomes against projected costs.
The dual benefit of repositioning the building on the plot, and the VAT saving tipped the balance. There is a clear environmental case for VAT reduction on 'deep green' retrofit projects, championed by a number of current campaigns (see Architects Journal 'retrofirst' campaign). We don’t demolish an existing building lightly - even a poorly performing bungalow of such minimal architectural merit. There were some remodel options which would have been exciting to follow through, but position, space, performance, quality and budget all weigh against the argument for re-use. Hopefully this equation will change in future
As well as the VAT saving, and the high performance of a new building, The rebuild allowed for repositioning of the building on the sloping, triangular plot - providing generous exterior spaces and views across the valley. Central to the brief were the creation of a welcoming entrance; a generous, private garden and, as ever, an extremely efficient building with as small an environmental footprint as possible. The finished two-storey house is only around 300mm higher than the ridge of the existing bungalow.
A relatively simple footprint was brought to life when considering the slope of the plot, which lead naturally to the split level arrangement which provides a 1.5 story high entrance lobby at upper ground floor. On arrival at the stairwell, one is greeted by an overview of the open plan living/dining space, and teasing glimpses of the exterior and views to the South West.
Passivhaus principles and full PHPP modelling were to be the driving force behind the technical element of the design. Insulation, airtightness, reduced overheating risk and cold-bridge elimination, MVHR, Solar PV and Airsource heat pump, as well as the pallet of wood based materials which have become a staple of our buildings.
The flat roof has been the subject of detailed discussion with building control. Unvented cold-roof construction is common on the continent, but is unconventional in the UK and as such required WUFI modelling to prove the condensation risk was acceptably low. The magic of the ‘variable diffusion membrane’ (Intello Plus in this case), combined with a dark single-ply membrane roof covering is the enabling factor.
Walls - 300mm Timber stud twin-wall, Warmcel insulation between, 60mm woodfibre panel over, rendered or clad
Roof - Unvented 'cold' Flat roof, Timber I joist
The dual benefit of repositioning the building on the plot, and the VAT saving tipped the balance. There is a clear environmental case for VAT reduction on 'deep green' retrofit projects, championed by a number of current campaigns (see Architects Journal 'retrofirst' campaign). We don’t demolish an existing building lightly - even a poorly performing bungalow of such minimal architectural merit. There were some remodel options which would have been exciting to follow through, but position, space, performance, quality and budget all weigh against the argument for re-use. Hopefully this equation will change in future
As well as the VAT saving, and the high performance of a new building, The rebuild allowed for repositioning of the building on the sloping, triangular plot - providing generous exterior spaces and views across the valley. Central to the brief were the creation of a welcoming entrance; a generous, private garden and, as ever, an extremely efficient building with as small an environmental footprint as possible. The finished two-storey house is only around 300mm higher than the ridge of the existing bungalow.
A relatively simple footprint was brought to life when considering the slope of the plot, which lead naturally to the split level arrangement which provides a 1.5 story high entrance lobby at upper ground floor. On arrival at the stairwell, one is greeted by an overview of the open plan living/dining space, and teasing glimpses of the exterior and views to the South West.
Passivhaus principles and full PHPP modelling were to be the driving force behind the technical element of the design. Insulation, airtightness, reduced overheating risk and cold-bridge elimination, MVHR, Solar PV and Airsource heat pump, as well as the pallet of wood based materials which have become a staple of our buildings.
The flat roof has been the subject of detailed discussion with building control. Unvented cold-roof construction is common on the continent, but is unconventional in the UK and as such required WUFI modelling to prove the condensation risk was acceptably low. The magic of the ‘variable diffusion membrane’ (Intello Plus in this case), combined with a dark single-ply membrane roof covering is the enabling factor.
Walls - 300mm Timber stud twin-wall, Warmcel insulation between, 60mm woodfibre panel over, rendered or clad
Roof - Unvented 'cold' Flat roof, Timber I joist
Credits
Architectural design- Henry Duncan, Greenheart
Structural design- George Holland, Element Structures
Energy Consultancy- Piers Sadler
Windows/doors- Ecovia
Cladding- Brimstone Ash (Vastern timber)
Architectural design- Henry Duncan, Greenheart
Structural design- George Holland, Element Structures
Energy Consultancy- Piers Sadler
Windows/doors- Ecovia
Cladding- Brimstone Ash (Vastern timber)
Stats
Airtightness- 1.1 m3/h/m2
Uvalues- (Average W/m2K)
Walls 0.12
Roofs 0.16
Ground floor 0.15
Openings 0.89
Airtightness- 1.1 m3/h/m2
Uvalues- (Average W/m2K)
Walls 0.12
Roofs 0.16
Ground floor 0.15
Openings 0.89