Hornbeams : 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 | - | 8323 kWh/yr | - |
|---|---|---|---|
| Natural gas use | - | - | - |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | - | 93 kWh/m².yr | - |
|---|---|---|---|
| Annual CO₂ emissions | - | 22 kg CO₂/m².yr | - |
| Annual space heat demand | - | 38 kWh/m².yr | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| Solar PV - monocrystalline silic | 10184 kWh/yr | - |
| Other Renewables Tech | - | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | -21 kWh/m².yr | - |
| Annual CO₂ emissions offset by renewable generation | -5 kg CO₂/m².yr | - |
Calculation and targets
| Whole house energy calculation method | PHPP |
|---|---|
| Other whole house calculation method | - |
| Energy target | AECB Silver |
| Other energy targets | - |
| Forecast heating load | 17 W/m² demand |
Airtightness
| Date | Result | |
| Pre-development air permeability test | - | - |
|---|---|---|
| Final air permeability test | 03 December 2024 | 1.36m³/m².hr @ 50 Pascals |
Project description
| Stage | Occupied |
|---|---|
| Start date | 17 May 2023 |
| Occupation date | 18 September 2024 |
| Location | Lavenham Suffolk England |
| Build type | New build |
| Building sector | Private Residential |
| Property type | Detached |
| Construction type | Softwood frame |
| Other construction type | timber frame, part steel, brick & render external |
| Party wall construction | n/a |
| Floor area | 224 m² |
| Floor area calculation method | Treated Floor Area (PHPP) |
| Building certification |
Project Team
| Organisation | Cayford - AECB Certifier |
|---|---|
| Project lead person | Project Orange |
| Landlord or Client | Private client |
| Architect | Project Orange |
| Mechanical & electrical consultant | Total Home Environment |
| Energy consultant | Total Home Environment + Cayford |
| Structural engineer | Superstructures |
| Quantity surveyor | Marstan BDB LLP |
| Consultant | |
| Contractor | Moore & Stone |
Design strategies
| Planned occupancy | Two people, mostly at home. |
|---|---|
| Space heating strategy | Heat Pump Ventilation (HPV) - air to air heat pump, for most of the heating demand, and some comfort cooling. Residual heat demand (in exceptionally cold weather) from built-in infra-red radiant panels. |
| Water heating strategy | Hot water is produced by a direct phase-change Sunamp thermal storage (heat battery) unit. There are Solar PV panels with battery to help power the hot water unit. |
| Fuel strategy | All electric no fossil fuel - heat-pump with Solar PV |
| Renewable energy strategy | Solar PV |
| Passive Solar strategy | Solar PV |
| Space cooling strategy | High thermal mass, eaves shading, fully opening windows on all four elevations. Mechanical air-supplied cooling is available from Heat Pump Ventilation unit. |
| Daylighting strategy | Windows and rooflights. |
| Ventilation strategy | Mechanical air-supplied fresh air ventilation with heat recovery from Heat Pump Ventilation unit. Fully opening windows on all four elevations |
| Airtightness strategy | Considerable care was taken for airtightness. The ground insulation is below the slab so the concrete slab is used for the floor air tightness. SIGA membranes and tapes are used on the inner lining of the insulation to walls and roofs. |
| Strategy for minimising thermal bridges | Continuous thermal insulation to minimise thermal bridging was a key part of the design. Thermal bridges were modelled for the floor-wall and wall-eaves junctions, and values recorded in PHPP. Where steel structural beams extend out of the thermal envelope armourflex structural thermal-breaks are installed to separate inside from outside, and external steel beams are wrapped with insulation. Ancon thermal resisting cavity ties are used where required. |
| Modelling strategy | The energy has been modelled with PHPP v10.4. We believe all elements have been completed accurately in the model, providing compliance with the AECB Carbonlight Legacy Standard. The project started at the end of 2022. The airtest result is n50 of 1.36 ACH. |
| Insulation strategy | Glapor recycled foam glass (RFG) gravel is laid to the thickness of 500 to 600 mm below the floor concrete floor slab. XPS foam provides thermal continuity at the slab edge to meet the walls. The walls and roofs are of timber frame construction. The joists are fully filled with a hemp-based quilt insulation, and Gutex wood-fibre batts are installed over the joists on the inside and the outside to eliminate the thermal bridge of the timber construction. (Similar construction for the roof). This also allows windows and doors to be installed with minimal thermal bridging. |
| Other relevant retrofit strategies | |
| Contextual information | Indoor air quality is managed by the filtered supply air from the HPV unit. There are no combustion appliances in the property, which helps external air quality. The house is set in the Suffolk countryside, and is locally surrounded by a verdant garden. |
Building services
| Occupancy | 3.1 modelled in PHPP. Likely occupancy is 2. |
|---|---|
| Space heating | HPV2 (Heat Pump Ventilation) air-to-air unit by Total Home Environments provides the majority of space heating requirement, distributed by insulated air-ducts. There are infrared panels in the sloping ceilings to provide back-up in exceptionally cold conditions. |
| Hot water | Hot water is produced by a direct phase-change Sunamp thermal storage (heat battery) unit. There are Solar PV panels with battery to help power the hot water unit. |
| Ventilation | HPV2 (Heat Pump Ventilation) unit by Total Home Environments provides fresh filtered air with heat recovery. Opening windows provide users with further choice. |
| Controls | Central touch-screen control panel, which is located within the main living area of the house. The panel allows the user to adjust all the important functions such as selection of the operating mode (e.g. ECO Summer which, during very warm periods, can reduce fan speeds during the day and facilitate greater and simultaneous use with the heat exchange bypass during the night to provide passive night-time cooling). The main control panel will allow the user to control the target room temperature for the main living area and for rooms with localised ceiling-mounted heater terminals, time settings and the 24 hr 7-day timer programme for specific temps and airflow rates throughout the week; display only of general system information, measured readings and reported errors; ventilation rates (essentially vacation, setback, standard and boost); domestic hot water heating settings; and system configuration settings for the administrators within the household. |
| Cooking | Induction electric |
| Lighting | LED |
| Appliances | Low energy appliances |
| Renewable energy generation system | Solar PV |
| Strategy for minimising thermal bridges | Continuous insulation was part of the design. Thermal bridges were modelled for the floor-wall and wall-eaves junctions. Where steel structural beams extend out of the thermal envelope armourflex structural thermal-breaks are installed to separate inside from outside, and external steel is wrapped in insulation. Ancon thermal resisting cavity ties are used where required. |
Building construction
| Storeys | 2 |
|---|---|
| Volume | 942m³ |
| Thermal fabric area | 814 m² |
| Roof description | The main roof is pitched, with additional flat roofs. a) Pitched roof: Timber rafter structure (with additional steelwork), joists filled with hemp-flax quilt, Gutex wood-fibre batts on top, with slate roof on battens & counter battens. Wood-wool boards with plaster ceilings.b) Flat roofs: Timber joist structure, joists filled with hemp-flax quilt, Gutex wood-fibre batts on top. Various ceiling finishes. |
| Roof U-value | 0.10 W/m² K |
| Walls description | Timber stud construction, fully filled with hemp-flax quilt. Inside - vapour membrane, Gutex wood-fibre batts, finished with self coloured lime plaster. Outside, breathable P5 particle board, Gutex wood-fibre batts, breathable membrane and cavity. Either render finish on woodwool board, or brick with insulating cavity ties. |
| Walls U-value | 0.10 W/m² K |
| Party walls description | n/a |
| Party walls U-value | - |
| Floor description | Reinforced concrete slab on 500-600mm Glapor recycled foam-glass (RFG). Isolating underlay with solid timber floor. |
| Floor U-value | 0.13 W/m² K |
| Glazed doors description | Aura triple-glazed, timber windows |
| Glazed doors U-value | 0.82 W/m² K uninstalled |
| Opaque doors description | Aura thermal solid front door |
| Opaque doors U-value | 1.80 W/m² K installed |
| Windows description | Aura triple-glazed, timber windows |
| Windows U-value | 0.78 W/m² K uninstalled |
| Windows energy transmittance (G-value) | 53 % |
| Windows light transmittance | 74% |
| Rooflights description | Skyway triple-glazed |
| Rooflights light transmittance | 54% |
| Rooflights U-value | 0.80 W/m² K |