Devoran Old School - The conversion of Grade II listed building into two dwellings
Download
as PDF This 1846 and subsequently extended School was designed by Pearson and is the central building of Devoran, Cornwall. The project is all about the sympathetic restoration and conversion of this high vaulted ceiling school into two adjoining homes. This is a family project which will eventually accommodate three generations of the same family.As this is a grade ii listed building a great deal of care needs to be taken about how we improve the thermal performance without unnecessarily impacting on the visual aspects of the building.While the cost of insulating and making the building air tight is not inconsiderable the major focus was to insulate the building using the most efficient and thinnest insulation materials available.Both propert...
Devoran Old School - The conversion of Grade II listed building into two dwellings : Project images
Click on image to preview full size
Energy and fuel use
Measured data from renewable generation is not yet available.
Fuel use
| Pre-development | Forecast | Measured | |
| Electricity use | - | - | - |
|---|---|---|---|
| Natural gas use | - | - | - |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | - | - | - |
|---|---|---|---|
| Annual CO₂ emissions | - | - | - |
| Annual space heat demand | - | - | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| Renewables Technology | - | - |
| Other Renewables Tech | - | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | - | - |
| Annual CO₂ emissions offset by renewable generation | - | - |
Calculation and targets
| Whole house energy calculation method | |
|---|---|
| Other whole house calculation method | - |
| Energy target | Self imposed - the highest affordable level for GII Listed Build |
| Other energy targets | - |
| Forecast heating load | - |
Airtightness
| Date | Result | |
| Pre-development air permeability test | - | - |
|---|---|---|
| Final air permeability test | - | - |
Project description
| Stage | Under construction |
|---|---|
| Start date | 14 November 2011 |
| Occupation date | 04 June 2012 |
| Location | Devoran Cornwall England |
| Build type | Refurbishment |
| Building sector | Private Residential |
| Property type | Semi-Detached |
| Construction type | Stone |
| Other construction type | Generally 600mm thick random rubble masonry. |
| Party wall construction | Block Wall |
| Floor area | 375 m² |
| Floor area calculation method | Approximate Floor Area |
| Building certification |
Project Team
| Organisation | Primary Conservation |
|---|---|
| Project lead person | Chris Hendra ~ Mark Roberts |
| Landlord or Client | Mark and Gilly Roberts ~ Andrew and Nicky Berry |
| Architect | Chris Hendra, Michael Hormann |
| Mechanical & electrical consultant | None |
| Energy consultant | None |
| Structural engineer | John Cormack |
| Quantity surveyor | Darrell Wilcock |
| Consultant | Terry Clarke |
| Contractor | John Kirwan |
Design strategies
| Planned occupancy | Middle School:The two properties address different occupancy requirements. One part of the school (Middle School) will be occupied by a retiring couple who are parents to the family occupying the adjoining property. It has 2 Bedrooms and an open plan living space representing 90% of the 120 metre building. There is a mezzanine level with work spaces providing access to the 2nd bedroom. High daily and night time occupancy by 2 people.The Old School:240 sq metres of ground floor space with two mezzanine levels accommodating a family of four in 3 bedrooms with an office family room capable of being converted into additional temporary accommodation. At home mother with working partner and school children. |
|---|---|
| Space heating strategy | All the floors are to be raised by an average of 300mm and this will provide accommodate underfloor heating. MVHR will be used in both properties with particular attention being placed on Kitchen Extraction and Ventilation. It is proposed to usea high efficiency filtration system with the MVHR being responsible for moisture removal and fresh air / heat distribution.Multi fuel fires will be used as supplementary heating. The prime source of heat is currently being investigated and dependent on how the SAP calculations turn out a decision will be made between mains gas or air source heat pumps. |
| Water heating strategy | Although the property is South and South East facing - it is also grade 2 listed. Careful consideration has to be given to the visual impact Solar heating will have on the building. Where there are roof valleys hidden from view then Solar Panels will be installed. These panels will heat The Old School water. As this project has yet to achieve planning the strategy to heat the water other than by gas / ashp will only be determined after consultation with the planning authority |
| Fuel strategy | Either Mains Gas or Mains Electricity |
| Renewable energy strategy | Subject to planning it is hoped to install 6 mtsq photovoltaic array. |
| Passive Solar strategy | We have designed a 16 cu mt south facing conservatory to act as a heat source through out the year. Once again this is subject to planning. The significant roof void will have the warm air extracted and fed into the MVHR using a summer/winter valve. Warm air will be used when required from the roof space. |
| Space cooling strategy | MVHR and natural ventilation with night purging during hot periods |
| Daylighting strategy | Using High Output T5 florescent tubes linked to daylight monitors will automatically adjust the light levels dependent on whether there are people in the building / rooms. Blinds will close automatically to reduce heat loss in winter. All lighting will be people and daylight sensitive. |
| Ventilation strategy | Comfort ventilation in the winter with natural ventilation - open windows etc in the summer |
| Airtightness strategy | The whole building is to be internally covered with Actis Triso Super 10 muti-foil insulation. Thisis to be secured at wall plate level and stapled and nailed to wooden battens forming an internal tent. The foil will be secured into the new solid concrete floor. All joints are to be taped - although because of the 1600mm width we do not envisage much cutting as the roof frames are all about 1500mm wide. This means that the foild membrane can be easily secured to the A Frames and then battened to take a Fermacell covering which will line the walls and ceilings.The one potential weakness are the windows where because of the Grade II listing we may not be able to replace the existing windows with bespoke double glazed units with comprehensive treatment to ensure an air tight fit. All existing windows will be - at the very least - refurbished to improve air tightness. |
| Strategy for minimising thermal bridges | As above the whole of the external structure is to be internally clad with a multi foil insulation which will sit in a 50mm air gap. Where it is impossible to use this strategy - like in the window reveals the use of an aerojel - Spacetherm backed Fermacell board will be used. This will have 10mm of Spacetherm as a minimum. This will be tucked into the foil insulation where the window reveals meet the newly insulated walls. |
| Modelling strategy | At this point no modelling has been undertaken |
| Insulation strategy | See above - Airtightness Stategy. The floors will be insulated with minimum 100mm EP and where this is unachievable then the most suitable alternative high performance insulation material will be used.Throughout the house the ceilings and walls will be covered with Actis Triso Super 10 multifoil insulation. This has been dictated because of the visual impact that any other thicker insulating material would have on the look and feel of the building. Where it is impossible to use this insulation then 10mm of Spacetherm aerojel will be used. The roof space that is flat will be additionally filled withan appropriate insulating material to be chosen at the time - based on UValues and cost. |
| Other relevant retrofit strategies | |
| Contextual information | This is a Grade II listed building, it is in a conservation area and it is the centre of a World Heritage Site. Anything that is proposed that causes the building to 'look different' is likely to be refused at planning. So it is intended to negotiate as much sustainable and energy producing / saving technologies as possible. |
Building services
| Occupancy | |
|---|---|
| Space heating | |
| Hot water | |
| Ventilation | |
| Controls | |
| Cooking | |
| Lighting | |
| Appliances | |
| Renewable energy generation system | |
| Strategy for minimising thermal bridges |
Building construction
| Storeys | |
|---|---|
| Volume | - |
| Thermal fabric area | - |
| Roof description | |
| Roof U-value | - |
| Walls description | |
| Walls U-value | - |
| Party walls description | |
| Party walls U-value | - |
| Floor description | |
| Floor U-value | - |
| Glazed doors description | |
| Glazed doors U-value | - - |
| Opaque doors description | |
| Opaque doors U-value | - - |
| Windows description | |
| Windows U-value | - - |
| Windows energy transmittance (G-value) | - |
| Windows light transmittance | - |
| Rooflights description | |
| Rooflights light transmittance | - |
| Rooflights U-value | - |