Wakefield and District Housing Kettlethorpe retrofit
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as PDF We are to carry out retrofit work to FOUR PROPERTIES on the Kettlethorpe estate. The properties selected for the works are 1945 - 1965 post war 3 bed semi-detached which account for a high proportion of Wakefield and District Housing stock. It is therefore fair to assume that a significant proportion of properties in the UK are built to these levels and standards and therefore these units will give excellent replicability to the works. The two pair of semis selected will be on the same estate, but on different roads as we want to compare units with gas to those without gas. The tenant profiles are also considerably different so there is the added advantage of monitoring not only different technologies but also different lifestyles
Retrofit for the future ZA644T
Wakefield and District Housing Kettlethorpe retrofit : Project images
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Energy and fuel use
Measured data from renewable generation is not yet available.
Fuel use
| Pre-development | Forecast | Measured | |
| Electricity use | 2033 kWh/yr | 1308 kWh/yr | 1601 kWh/yr |
|---|---|---|---|
| Natural gas use | 18213 kWh/yr | 8039 kWh/yr | 3241 kWh/yr |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | 315 kWh/m².yr | 152 kWh/m².yr | 94 kWh/m².yr |
|---|---|---|---|
| Annual CO₂ emissions | 60 kg CO₂/m².yr | 29 kg CO₂/m².yr | 20 kg CO₂/m².yr |
| Annual space heat demand | - | 4847 kWh/m².yr | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| photovoltaics | 1914 kWh/yr | - |
| Other Renewables Tech | - | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | 94 kWh/m².yr | 94 kWh/m².yr |
| Annual CO₂ emissions offset by renewable generation | 15 kg CO₂/m².yr | 20 kg CO₂/m².yr |
Calculation and targets
| Whole house energy calculation method | SAP |
|---|---|
| Other whole house calculation method | The basis of the calculations is SAP, feeding into the extension spreadsheet. Some houses will have a large solar thermal system |
| Energy target | Retrofit for the Future |
| Other energy targets | - |
| Forecast heating load | - |
Airtightness
| Date | Result | |
| Pre-development air permeability test | 26 March 2010 | 7.46m³/m².hr @ 50 Pascals |
|---|---|---|
| Final air permeability test | 03 March 2011 | 4.25m³/m².hr @ 50 Pascals |
Project description
| Stage | Under construction |
|---|---|
| Start date | 12 April 2010 |
| Occupation date | 30 July 2010 |
| Location | Wakefield West Yorkshire England |
| Build type | Refurbishment |
| Building sector | Public Residential |
| Property type | Semi-Detached |
| Construction type | Masonry Cavity |
| Other construction type | |
| Party wall construction | |
| Floor area | 82.6 m² |
| Floor area calculation method | Treated Floor Area (PHPP) |
| Building certification |
Project Team
| Organisation | Bramall Construction |
|---|---|
| Project lead person | Nick O'Connor; Bramall Construction |
| Landlord or Client | Owen Daggett; Wakefield and District Housing |
| Architect | Charlie Baker; URBED (Manchester) |
| Mechanical & electrical consultant | Nigel Banks, AECOM (Leeds) |
| Energy consultant | |
| Structural engineer | |
| Quantity surveyor | Bramall Construction |
| Consultant | |
| Contractor | Bramall Construction |
Design strategies
| Planned occupancy | All 4 of the properties are 3 bedroom, currently tenanted as follows: 1 adult 1 Child;1 adult 1 child, 2 adults 3 children. 2 adults 2 children. |
|---|---|
| Space heating strategy | 3 of the 4 properties will be heated by their existing radiators. In 7 & 9 they will be heated by gas boilers, one a very small 3.5-11kw condensing boiler, the other a high modulating standard sized condensing boiler. In 43 the majority of the radiators will be removed (2 back up rads to remain). The heating will be provided through the ventilation system heated by a Drexel und Weiss combined exhaust air heat pump and MVHR unit. 41 will retain its radiators, the heat will come from a large stratifying thermal store fed by 8sq.m. (aperture area) of evacuated solar tubes providing 25% of the space heating the rest from a 3kW immersion element in tank. |
| Water heating strategy | The boilers in A and B will be combis as they have currently. In D most of hot water will be provided by the solar thermal array -50- 60% with the rest provided by the exhaust air heat pump of the Drexel und Weiss. There will be also be immersion back up. In C, 85% of the hot water will come from the solar array, with the tank of a size to buffer for poor weather. The immersion back up will provide the remainder |
| Fuel strategy | Main gas and mains electricity to A and B. Mains electric only to C and D. |
| Renewable energy strategy | A and B will both have 2.4kW photovoltaic arrays |
| Passive Solar strategy | In all 4 properties while the windows are being replaced the openings are remaining unchanged. However the new windows will be fixed to the front of new timber reveals to come nearly flush with the outside surface of the render. This will maximise solar gain as much as is possible.41 & 43 will have solar buffer spaces created between the house and the former coal stores. The Drexel und Weiss unit will make use of the warmer air in here for heating the rest of no.43. No.41's MVHR unit will draw inlet air from this space increasing its efficiency. |
| Space cooling strategy | A will supplement the exisiting natural ventilation with a temperature actuated loft hatch and permanent vent to the retained chimney just below the ridge. Together with the existing windows this will provide stack effect ventilation during heat waves without needing to undermine security with windows open all night. B will have stack effect ventilation so the stack will increase in force during hot periods C and D will have their night purge on the MVHR supplemented by the same loft and vent combination as A. |
| Daylighting strategy | The existing windows opening are not being changed, this has not been changed. Moving the windows to the outside of the envelope will mitigate the reduction in sky view as a result of the thicker wall. |
| Ventilation strategy | A will rely on existing natural ventilation supplemented by the loft stack system described above. B will be fitted with a Passivent passive stack ventilation system C and D will have whole house ventilation, again supplemented by the loft stack system when necessary. |
| Airtightness strategy | The new double seal windows will be pre-fitted and shop sealed to the new reveals which will be fitted prior to the external insulation allowing them to be taped to the existing masonry outside and sealed with a mastic seal internally. The render is a modified polymer and will be carried past the woodfibre insulation making a seal with the foamglas below ground insulation. At roof level it will be sealed to the eaves board vertically and back to the sole plate internally. The ceilings will be resealed and the hatches are all to be replaced with actuated and sealed insulated ones. Floors are ground bearing concrete under the timber. |
| Strategy for minimising thermal bridges | The window detail described above ensures a continuous insulation all the way to the window. The front door detail will not come right to the fron but will protrude past the masonry to ensure no bridging. The insulation is continuous 600mm past the floor edge. The ceilings are being topped up with Warmcel so filling gaps. The loft hatch is being replaced with an insulated one achieving 0.35W/m2K. On the gables the insulation will be carried past to form a parapet and so avoid any bridging. The external insulation at the eaves will be joined to the internal ceiling insulation with a high efficiency insulation as the accredited detail. |
| Modelling strategy | |
| Insulation strategy | All the rafters are to be build up into 400mm timber beams through the addition of plywood web pieces and an additional rafter. Warmcel will be poured over the existing insulation up to the rafter tops and then boarded in to prevent disturbance and compression. All the walls will be insulated externally with 200mm of Udireco wood fibre insulation - a compressible internal layer bonded to a higher density rigid board that takes a reinforced modified polymer diffusion open render system. 300mm above ground the wood fibre will be replaced by 200mm of Foamglas slabs. In addition the floors in two of the properties will be replaced with 200mm of Misapor granular foamed glass under a new concrete slab. The doors will be insulated, all the windows triple glazed. |
| Other relevant retrofit strategies | The tenants have been involved in picking the measures from the start and they have been tailored to suit their preferences where possible. They have been fully explained, and further support visits are planned. The intention is that in A and B the tenants will remain in the properties throughout. The tenants of C and D wanted the new floors so will be temporarily rehoused while this part of the work is carried out. |
| Contextual information |
Building services
| Occupancy | NULL |
|---|---|
| Space heating | NULL |
| Hot water | NULL |
| Ventilation | NULL |
| Controls | NULL |
| Cooking | NULL |
| Lighting | NULL |
| Appliances | NULL |
| Renewable energy generation system | NULL |
| Strategy for minimising thermal bridges | NULL |
Building construction
| Storeys | |
|---|---|
| Volume | - |
| Thermal fabric area | - |
| Roof description | NULL |
| Roof U-value | 0.00 W/m² K |
| Walls description | NULL |
| Walls U-value | 0.00 W/m² K |
| Party walls description | NULL |
| Party walls U-value | 0.00 W/m² K |
| Floor description | NULL |
| Floor U-value | 0.00 W/m² K |
| Glazed doors description | NULL |
| Glazed doors U-value | 0.00 W/m² K - |
| Opaque doors description | NULL |
| Opaque doors U-value | 0.00 W/m² K - |
| Windows description | NULL |
| Windows U-value | 0.00 W/m² K - |
| Windows energy transmittance (G-value) | - |
| Windows light transmittance | - |
| Rooflights description | NULL |
| Rooflights light transmittance | - |
| Rooflights U-value | 0.00 W/m² K |