Thamesmead Retrofit House
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as PDF This highly ambitious project aimed to refurbish a pre-cast concrete panel end terrace in the Thamesmead Estate, South-East London. The team created an innovative, robust and replicable refurbishment solution, which cut 80% of the dwellings carbon emissions, achieving high levels of comfort at attractive costs. The property was transformed from a four bedroom hard-to-treat property into a six bedroom super-insulated home supporting a 7-person family. The scheme includes external cladding, triple glazing and high levels of air tightness. Fresh air is provided by a mechanical ventilation system with heat recovery (MVHR). Ten photovoltaic (PV) panels and a vacuum tube collector on the roof provide renewable electricity and water heating. A gas boiler is provided to meet the peak heating load. A key innovation is a highly-insulated solar-air heater containing a super-insulating aerogel cover integrated into the external insulation on the south faade pre-heating the MVHR on cold sunny days.
Retrofit for the future ZA275R
Thamesmead Retrofit House : Project images
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Energy and fuel use
Renewable electricity generation This project has used the contributions from renewable electricity generation equipment to either meet the Retrofit for the Future target or otherwise reduce the Primary energy requirement and CO₂ emissions associated with the project.
Measured data from renewable generation is not yet available.
Fuel use
| Pre-development | Forecast | Measured | |
| Electricity use | 7894.93 kWh/yr | 2764.56 kWh/yr | 3475 kWh/yr |
|---|---|---|---|
| Natural gas use | 66506.65 kWh/yr | 8157.95 kWh/yr | 9075 kWh/yr |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | 550 kWh/m².yr | 93 kWh/m².yr | 109 kWh/m².yr |
|---|---|---|---|
| Annual CO₂ emissions | 105 kg CO₂/m².yr | 19 kg CO₂/m².yr | 22 kg CO₂/m².yr |
| Annual space heat demand | 542.25 kWh/m².yr | 28 kWh/m².yr | 39.7 kWh/m².yr |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| 2.3 kWp photovoltaic panels | 1923 kWh/yr | 2138.64 kWh/yr |
| Other Renewables Tech | - | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | 66 kWh/m².yr | 78 kWh/m².yr |
| Annual CO₂ emissions offset by renewable generation | 13 kg CO₂/m².yr | 15 kg CO₂/m².yr |
Calculation and targets
| Whole house energy calculation method | SAP |
|---|---|
| Other whole house calculation method | * Pre-development utility figures were generated through SAP modelling which may significantly overestimate consumption |
| Energy target | Retrofit for the Future |
| Other energy targets | - |
| Forecast heating load | - |
Airtightness
| Date | Result | |
| Pre-development air permeability test | 19 April 2010 | 7.65m³/m².hr @ 50 Pascals |
|---|---|---|
| Final air permeability test | 22 March 2012 | 2.94m³/m².hr @ 50 Pascals |
Project description
| Stage | Occupied |
|---|---|
| Start date | 01 November 2010 |
| Occupation date | 02 March 2012 |
| Location | Thamesmead London England |
| Build type | Refurbishment |
| Building sector | Public Residential |
| Property type | End Terrace |
| Construction type | Concrete frame |
| Other construction type | 255mm precast concrete panel embedded with 50mm polystyrene |
| Party wall construction | 180mm concrete with re-inforced bars / timber rafters |
| Floor area | 174.9 m² |
| Floor area calculation method | Actual Floor Area (SAP) |
| Building certification |
Project Team
| Organisation | Fraser Brown MacKenna & Buro Happold |
|---|---|
| Project lead person | Fraser Brown MacKenna & Buro Happold |
| Landlord or Client | Gallions Housing Association |
| Architect | Fraser Brown Mackenna Architects |
| Mechanical & electrical consultant | Buro Happold |
| Energy consultant | Buro Happold |
| Structural engineer | Buro Happold |
| Quantity surveyor | Martin-Arnold Associates |
| Consultant | |
| Contractor | Axis Europe |
Design strategies
| Planned occupancy | 7 person family; unpredictable weekday habits. |
|---|---|
| Space heating strategy | Heating: Warm air supplied by MVHR pre-heated by Aerogel Solar Collector. System boiler with small-zoned radiators for peak winter conditions. |
| Water heating strategy | Hot water: 500 litre cylinder fed by electric immersion and boiler. A roof mounted solar thermal system (3m2 vacuum tube collector) meets 42% of load. |
| Fuel strategy | Solar power (PV, solar thermal, solar pre-heat to MVHR), mains electricity & gas. |
| Renewable energy strategy | Electricity generation: Ten PV panels generate 2.30 kW peak. Array is ballasted using aluminium frame to avoid piercing insulation. |
| Passive Solar strategy | A roof mounted solar thermal system (3m2 vacuum tube collector) meets 42% of hot water requirements. 6m x 0.9m Aerogel Solar Collector on south facade. Extract air from dwelling fed into cavity, to provide additional energy to pre-heat incoming supply air to property. During a seven-day controlled test in October, the solar collector outlet reached 45C on a cold sunny day, preheating the supply air in the mechanical ventilation system to 30C, enabling the house to maintain comfortable living conditions at 21-22C, without additional heating. |
| Space cooling strategy | Natural ventilation through window opening in all rooms, cross ventilation possible. Thermal mass of dwelling retained to aid in balancing thermal swing throughout the day. MVHR has automatic summer bypass switch. |
| Daylighting strategy | Kitchen area exceeds minimum Code for Sustainable Homes recommended average daylight factor of 2%, achieving at least 2.5%. Additionally the living area achieves at least 3% average daylight factor. |
| Ventilation strategy | Nuaire MRXBOX95B-WH1 unit with summer bypass. Extract air for heat recovery boosted by Aerogel Solar Collector. Openable windows for purging and summer time ventilation. |
| Airtightness strategy | We used a PermaRock overcladding system, a lightweight polystyrene insulation which has a robust external render and is adhered to the outside of the existing walls. It is easier to block rogue air-pathways using consistent, large panel overcladding than it is using cavity wall or internal insulation. There is less risk in this approach because the state of existing materials and components in difficult to reach areas is less significant, as is the quality of workmanship required. We also know that the movement between concrete panels in a Balency system is minimal so we were free to clad over joints, further increasing the airtightness. |
| Strategy for minimising thermal bridges | We used the thermal bridge-free approach as defined by Passivhaus Institute. Overcladding is better for minimising thermal bridging than cavity or internal insulation. This is because it uniformly isolates the existing build-up from the external environment, cutting-off any existing thermal bridges at cold end, which also reduces the risk of interstitial condensation. |
| Modelling strategy | SAP modelling was undertaken using IES Virtual Environment and JPA Designer. Results were fed into TSB spreadsheet to provide whole house energy performance. Architectural drawings were produced using Revit 10. PHPP was used to undertake preliminary Passivhaus/EnerPHit calculations. |
| Insulation strategy | Our aim was to find a cost-effective approach to over-cladding that retains as much heat as possible, utilising Passivhaus insulation and air-tightness values, whilst also making best use of the beneficial thermal mass already present in the concrete walls. After examining a range of options we decided on the PermaRock cladding system: a lightweight polystyrene insulation with a robust external render. It is adhered to the outside of the existing walls. The 300mm insulation thickness vastly improves the thermal perfomance of the wall and makes better use of the thermal mass. The solution is durable, robust, and fire-resistant, plus it will resist water penetration and reduce the risk of interstitial condensation. |
| Other relevant retrofit strategies | Walls: 300 mm of Permarock EPS insulation to achieve U-value of 0.1 W/m2K. Roof: New roof with airtight membrane, services core and 300mm of PIR insulation to achieve a U-value of 0.1 W/m2K.Windows: Passivhaus-certified Nordan N-tech triple glazing with U-value of 0.8 W/m2.K and solar G-value of 0.5Doors: Passivhaus-certified front door achieving a U-value of 0.8 W/m2.K. Custom built double leaf plant room door (by Proctor Group) containing Spacetherm aerogel blankets achieving a U-value of 0.65 W/sq m.KGround floor: U-value of 0.15 W/sq m.K throughout. Spacetherm aerogel insulation used in zones where 80mm space available.Air tightness: Pro Clima airtight tapes, sealants and sleeves used throughout. Target: 0.6 m3/m2.hr @50 Pa. Best on-site : 2.94 m3/m2.hr @50 Pa. |
| Contextual information | We have specified external render with a very high impact resistance to withstand the rough and tumble of everyday use. |
Building services
| Occupancy | 7 person family; unpredictable weekday habits. |
|---|---|
| Space heating | Heating: Warm air supplied by MVHR pre-heated by Aerogel Solar Collector. System boiler with small-zoned radiators for peak winter conditions. |
| Hot water | Hot water: 500 litre cylinder fed by electric immersion and boiler. A roof mounted solar thermal system (3m2 vacuum tube collector) meets 42% of load. |
| Ventilation | Nuaire MRXBOX95B-WH1 unit with summer bypass. Extract air for heat recovery boosted by Aerogel Solar Collector. Openable windows for purging and summer time ventilation. |
| Controls | The MVHR system runs continuously with a summer bypass to prevent overheating in summer. Gas boiler for peak winter demand provides zoned time and temperature controlled heating, through the use of thermostatic radiator valves and thermostats on each floor. Small radiators were provided in each room. |
| Cooking | All cooking equipmentwas purchased through Gallions Housing Association. Gas is still used in the property for cooking purposes. |
| Lighting | Throughout the property new low energy light bulbs and fittings were installed. |
| Appliances | All white goods were purchased through Gallions Housing Association. |
| Renewable energy generation system | Electricity generation: Ten PV panels generate 2.30 kW peak. Array is ballasted using aluminium frame to avoid piercing insulation. |
| Strategy for minimising thermal bridges | We used the thermal bridge-free approach as defined by Passivhaus Institute. |
Building construction
| Storeys | 3 |
|---|---|
| Volume | 448.81m³ |
| Thermal fabric area | 297 m² |
| Roof description | New timber joists were constructed and the surface was insulated and lined with a continuous airtight roof membrane and 300 mm of Celotex polyurethane insulation to achieve a U-value of 0.1 W/m2 K. To minimise penetrations, a core was created for services cables and pipes, sealed using airtight sleeves beneath the insulation layer. |
| Roof U-value | 0.10 W/m² K |
| Walls description | External cladding was installed by Permarock Products Ltd approved installers. To achieve a U-value of 0.15 W/m2 K, a 300 mm layer of expandedpolystyrene insulation was bonded with adhesives and pinned in place. |
| Walls U-value | 0.15 W/m² K |
| Party walls description | |
| Party walls U-value | - |
| Floor description | To seal the ground floor, airtight tapes and membranes were applied to the internalperimeter of the building. An overall U-value of 0.15 was achieved. 80mm Spacetherm aerogel insulation was used in an area with limited floor to ceiling height. Cellotex insulation was used in all other areas. |
| Floor U-value | 0.15 W/m² K |
| Glazed doors description | On the ground floor, the new kitchen contain floor-to-ceiling N-tech triple glazing and a triple glazed door leading into the garden. These products have a U-value of 0.8 W/m2 K. |
| Glazed doors U-value | 0.80 W/m² K installed |
| Opaque doors description | The entrance door to the property is a Passivhaus certified Internorm door with a U-value of 0.8 W/m2 K . A custom-built external plant room door with a U-value of 0.65 W/m2 K was constructed by Proctor Group Ltd. |
| Opaque doors U-value | 0.80 W/m² K - |
| Windows description | For the glazing, Nordan UKs N-tech triple glazing was specified throughout the property. These Passivhaus certified units possess an overall U-value of 0.7 W/m2 K and solar g-value of 0.5. All existing windows were removed and timber boxes to reduce thermal bridging were created to house the new units. |
| Windows U-value | 0.70 W/m² K - |
| Windows energy transmittance (G-value) | 50 % |
| Windows light transmittance | 58% |
| Rooflights description | n/a |
| Rooflights light transmittance | - |
| Rooflights U-value | - |