Skylarks
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as PDF Deep retrofit of an existing 1960s detached house. The key principles of passive house building design were followed to minimise the primary energy demand of the house.
Skylarks : 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 | 3163 kWh/yr | 2894 kWh/yr | 5057 kWh/yr |
|---|---|---|---|
| Natural gas use | - | - | - |
| Oil use | 19572 kWh/yr | - | - |
| LPG use | 45 kWh/yr | - | - |
| Wood use | 2400 kWh/yr | 1640 kWh/yr | 7665 kWh/yr |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | 151 kWh/m².yr | 40 kWh/m².yr | 94 kWh/m².yr |
|---|---|---|---|
| Annual CO₂ emissions | 33 kg CO₂/m².yr | 8 kg CO₂/m².yr | 14 kg CO₂/m².yr |
| Annual space heat demand | 91 kWh/m².yr | 23 kWh/m².yr | 13.3 kWh/m².yr |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| PV | 4188 kWh/yr | 4188 kWh/yr |
| Other Renewables Tech | - | - |
| Electricity consumed by generation | - | 2094 kWh/yr |
| Primary energy requirement offset by renewable generation | -7 kWh/m².yr | 71 kWh/m².yr |
| Annual CO₂ emissions offset by renewable generation | -3 kg CO₂/m².yr | 9 kg CO₂/m².yr |
Calculation and targets
| Whole house energy calculation method | PHPP |
|---|---|
| Other whole house calculation method | - |
| Energy target | AECB Level 2 Retrofit Standard |
| Other energy targets | - |
| Forecast heating load | 16 W/m² demand |
Airtightness
| Date | Result | |
| Pre-development air permeability test | - | - |
|---|---|---|
| Final air permeability test | 13 October 2022 | 1.57m³/m².hr @ 50 Pascals |
Project description
| Stage | Occupied |
|---|---|
| Start date | 27 September 2021 |
| Occupation date | 15 April 2022 |
| Location | Battisborough Cross Devon England |
| Build type | Refurbishment |
| Building sector | Private Residential |
| Property type | Detached |
| Construction type | Masonry Cavity |
| Other construction type | First floor is timber frame |
| Party wall construction | n/a |
| Floor area | 225 m² |
| Floor area calculation method | Treated Floor Area (PHPP) |
| Building certification |  AECB silver standard certified building |
Project Team
| Organisation | Rob Rickey Design |
|---|---|
| Project lead person | Rob Rickey |
| Landlord or Client | Dr. Simon Martin and Dr. Nirosha Gunnatilake |
| Architect | Rob Rickey |
| Mechanical & electrical consultant | Greengauge Building Energy Consultants |
| Energy consultant | Rob Rickey |
| Structural engineer | Nigel Ridley |
| Quantity surveyor | |
| Consultant | |
| Contractor | Futureproof Building |
Design strategies
| Planned occupancy | Four persons - at work or school all day |
|---|---|
| Space heating strategy | Use existing radiators heated by Steibel Eltron 7kw air source heat pump. A lower output 4kw modern woodburner with a dedicated air supply was installed to replace the 8kw older model. |
| Water heating strategy | 300L Cylinder storage within the thermal envelope. This is heated by an air source heat pump timed to use excess solar PV during midday-early afternoon. This 7kw Steibel Eltron pump efficiency is: 1kw of electrical energy creates a measured output of 3.9kw of heat energy for the hot water system at Skylarks. |
| Fuel strategy | Mains electricity. Wood. |
| Renewable energy strategy | Use existing 4kWp array connected to offset any grid use by the air source heat pump, MVHR and all sockets with high use such as dishwasher/washing machine and outside plugs used to slow charge electric vehicles. Measured output is 4188kWH per annum. |
| Passive Solar strategy | Glazing size and orientation optimised using DesignPH and PHPP. Glazed area was reduced to 40% of treated surface area to minimise heat loss and overheating risk. |
| Space cooling strategy | Active by MVHR on summer bypass mode to cool house overnight. Natural cross ventilation due to east west orientation of house with prevailing Westerly coastal breeze. Window reveal depth of 250mm provides shading from direct overhead summer sun. Triple glazed glass has low Thermal Gain value. The 2 flat roof lights have external shade available to minimise gain. |
| Daylighting strategy | Re-use of existing openings. |
| Ventilation strategy | Zehnder Q450 MVHR with summer bypass function. This model is a Passivhaus institute certified component and has a 96% heat recovery minimising heat loss by ventilation. The intake and extract ducts to the MVHR unit were kept as short as possible. The insulated ducts were encased in rockwool in their dedicated boxing from outside to the unit (1.2m). |
| Airtightness strategy | Install airtightness layer on the outside of the existing structure using Passive Purple liquid membrane on walls and SmartPly Propassiv OSB on existing rafters. Join systems and windows, with Sega airtightness tapes and insulate outside of this layer. |
| Strategy for minimising thermal bridges | By using external insulation, care taken to ensure that all junctions were formed by insulation meeting insulation. Major junctions modelled in Therm to calculate psi-values. Triple glazed Passivhaus institute certified Progression windows were used. This allows the head and jamb of each window installation to be covered with insulation to improve sci values at these junctions. The sill rests on compact foam. |
| Modelling strategy | Model in Sketchup using DesignPH to optimise glazing ratio and balance insulation, then transfer to PHPP. |
| Insulation strategy | *Remove roofing, install insulation between and above rafters to achieve U-value of 0.156 W/m2K*Insulate masonry walls with wood fibre insulation to achieve U-value of 0.141 W/m2K*Construct new sunroom timber frame wall with infill insulation; U-value of 0.126 W/m2K*Insulate timber framed upper story with wood fibre insulation to achieve U-value of 0.125 W/m2K |
| Other relevant retrofit strategies | Extend wall and floor perimeter insulation to the integral garage to future-proof this space for inclusion in the heated area of the house. |
| Contextual information |
Building services
| Occupancy | Family of four |
|---|---|
| Space heating | 7Kw Air source heat pump with radiators. Each radiator is linked to the air source heat pump control to allow continual feedback of room temperature. This is the Easitron Steibel Eltron system. |
| Hot water | 7Kw Air source heat pump300L Cylinder storage within the thermal envelope. This is heated by an air source heat pump timed to use excess solar PV during midday-early afternoon. This 7kw Steibel Eltron pump efficiency is: 1kw of electrical energy creates a measured output of 3.9kw of heat energy for the hot water system at Skylarks. |
| Ventilation | Zehnder Q450 MVHR with summer bypass function. This model is a Passivhaus institute certified component and has a 96% heat recovery minimising heat loss by ventilation. The intake and extract ducts to the MVHR unit were kept as short as possible. The insulated ducts were encased in rockwool in their dedicated boxing from outside to the unit (1.2m). |
| Controls | Air temperature thermostatic and programmer.Steibel Eltron system with communication between radiators and heat pump. End user can control system remotely. System has a passiv haus insulated house setting and stays in summer bypass mode until measured external temperature drops below 10 degrees over 72 hours. |
| Cooking | Induction hob, 2 "AAA" rated electric ovens |
| Lighting | LED |
| Appliances | |
| Renewable energy generation system | Solar PV (12xSunpower panels producing 3.924Kw groos) |
| Strategy for minimising thermal bridges | External insulation on roof, walls and foundation walls below ground. The inward opening Progression windows frame and head have been concealed by insulation. |
Building construction
| Storeys | 2 |
|---|---|
| Volume | 563m³ |
| Thermal fabric area | 692 m² |
| Roof description | 100mm Wood fibre between existing joists; 140mm wood fibre insulation on top of airtight deck; standing seam metal roofing |
| Roof U-value | 0.17 W/m² K |
| Walls description | Existing masonry walls: 200mm wood fibre insulation between i-joists; render or timber cladding.Existing timber walls: |
| Walls U-value | 0.14 W/m² K |
| Party walls description | N/A |
| Party walls U-value | 0.00 W/m² K |
| Floor description | Concrete floor slab throughout; partly insulated |
| Floor U-value | 0.25 W/m² K |
| Glazed doors description | 1.Rationel Auraplus triple glazed door |
| Glazed doors U-value | 0.79 W/m² K uninstalled |
| Opaque doors description | Internorm AT400 Aluminium |
| Opaque doors U-value | 0.75 W/m² K uninstalled |
| Windows description | Slavona Progression triple glazed window |
| Windows U-value | 0.68 W/m² K uninstalled |
| Windows energy transmittance (G-value) | 0.542 % |
| Windows light transmittance | 0.74% |
| Rooflights description | Velux triple glazed units |
| Rooflights light transmittance | 0.73% |
| Rooflights U-value | 0.83 W/m² K |
Skylarks : Download Files
4.pdf (223.37 KB) Air_Pressure_Certificate.pdf (89.65 KB) PDFen-merged.pdf (3.9 MB) Skylarks_FF_Plan.pdf (324.42 KB) Skylarks_Floor-Wall_junction.pdf (138.61 KB) Skylarks_GF_Plan.pdf (372.33 KB) Skylarks_Intermediate_Floor_Junction.pdf (120.87 KB) Skylarks_Roof-Wall_detail.pdf (143.6 KB) Skylarks_Sec_1_rev_A.pdf (491.2 KB) Skylarks_Service_penetration.pdf (129.29 KB) Skylarks_Verification_Page.pdf (306.78 KB) Skylarks_Window_Cill_detail.pdf (139.91 KB) Skylarks_Window_Jamb_detail.pdf (143.14 KB) Skylarks_Window_head_detail.pdf (144.15 KB)