Retrofit of Victorian mid-terrace in Ladybarn, Manchester
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as PDF This was a renovation project of a solid-walled house built in 1888, located in Ladybarn, Manchester. The work included both energy efficiency retrofit measures (e.g. insulation, MVHR) in tandem with some other work as part of the renovation.The energy efficiency measures revolved largely around insulation, airtightness and ventilation.
Retrofit of Victorian mid-terrace in Ladybarn, Manchester : Project images
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Fuel use
| Pre-development | Forecast | Measured | |
| Electricity use | 752.8 kWh/yr | - | 789 kWh/yr |
|---|---|---|---|
| Natural gas use | 6244.5 kWh/yr | - | 4524 kWh/yr |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | 150 kWh/m².yr | - | 119 kWh/m².yr |
|---|---|---|---|
| Annual CO₂ emissions | 29 kg CO₂/m².yr | - | 23 kg CO₂/m².yr |
| Annual space heat demand | 258.9 kWh/m².yr | 89 kWh/m².yr | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| Renewables Technology | - | - |
| Other Renewables Tech | - | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | - | 119 kWh/m².yr |
| Annual CO₂ emissions offset by renewable generation | - | 23 kg CO₂/m².yr |
Calculation and targets
| Whole house energy calculation method | PHPP |
|---|---|
| Other whole house calculation method | - |
| Energy target | |
| Other energy targets | - |
| Forecast heating load | 36.6 W/m² demand |
Airtightness
| Date | Result | |
| Pre-development air permeability test | 30 May 2013 | 12.725m³/m².hr @ 50 Pascals |
|---|---|---|
| Final air permeability test | 13 October 2013 | 1.19m³/m².hr @ 50 Pascals |
Project description
| Stage | Occupied |
|---|---|
| Start date | 20 May 2013 |
| Occupation date | 12 November 2013 |
| Location | Manchester Manchester England |
| Build type | Refurbishment |
| Building sector | Private Residential |
| Property type | Mid Terrace |
| Construction type | Solid Brick |
| Other construction type | 245mm solid brick with finger cavity |
| Party wall construction | |
| Floor area | 60.54 m² |
| Floor area calculation method | Treated Floor Area (PHPP) |
| Building certification |
Project Team
| Organisation | ColdProof |
|---|---|
| Project lead person | Eric Fewster |
| Landlord or Client | Ruth Shepherd |
| Architect | |
| Mechanical & electrical consultant | |
| Energy consultant | Eric Fewster |
| Structural engineer | |
| Quantity surveyor | |
| Consultant | |
| Contractor | Expert Home Extensions |
Design strategies
| Planned occupancy | One person living in the house. |
|---|---|
| Space heating strategy | Heating to be from mains gas-fired boiler feeding radiators; heat recovered from whole house ventilation exhaust. |
| Water heating strategy | Water heated using mains gas-fired boiler only. |
| Fuel strategy | Mains gas, mains electricity (but since 2015 from 100% renewable supplier). |
| Renewable energy strategy | |
| Passive Solar strategy | |
| Space cooling strategy | |
| Daylighting strategy | |
| Ventilation strategy | MVHR unit to be installed, openable windows for summer. |
| Airtightness strategy | Airtightness to be achieved using attention to detail at all parts of renovation process. 3 fan tests planned, breathable membrane to be used in front of internal insulation and across first floor ceilings (including passing across top of stud wall), areas of walls within floor voids to be exposed and plastered (for both external and party walls). |
| Strategy for minimising thermal bridges | Thermal bridge modelling to be done on all junctions to reduce heat loss as much as practically possible. |
| Modelling strategy | Whole house modelling was undertaken in PHPP for both pre- and post-retrofit scenarios. |
| Insulation strategy | Wood fibre boards to be fixed internally direct onto external-facing walls (no timber studwork needed). Extruded polystyrene laid over existing solid floor - thickness to be determined by existing door thresholds. Mineral wool insulation for the loft space. |
| Other relevant retrofit strategies | Moisture management was important to get right for both the external solid walls and chimney breasts. For the walls, a combination of wood fibre and external coat of Keim Lotexan mineral paint to repel driven rain was planned. For chimney breasts, we planned to seal off the air vents, yet reduce moisture risk by filling the void with Leca beads, adding a chimney cap to the cowl, painting chimney stack with Keim Lotexan, and removing a brick in the chimney within the loft space to allow air to circulate. |
| Contextual information | This project was carried out by myself as energy consultant and project manager. All of the work was done by builders and myself as part of that team (rather than the client). The predicted budget was almost half what was actually spent, but this was a learning project and valuable data on hours spent on each individual improvement was gained as a result. Some compromises were made due to budget available, as well as existing structure (e.g. double glazed windows had recently been put in, and although not high-performing in terms of energy, it did not make sense to take them out). The pre-retrofit gas readings were low since the client had a low average house temperature (only heated 2 rooms). |
Building services
| Occupancy | One person living in the house. |
|---|---|
| Space heating | Heating from mains gas-fired boiler feeding radiators; heat recovered from ventilation exhaust. |
| Hot water | Water heated using mains gas-fired boiler only. |
| Ventilation | Brink Sky 300 MVHR unit with an installed (effective) heat recovery efficiency (according to PHPP) of 73.2%. The unit has self-balancing fans, summer bypass and a pre-heating element for cold weather. Air flow is pre-calculated according to the number of bends and length of duct - actual flow is then restricted accordingly at the manifold prior to distribution to the various terminals. Existing windows openable for summer ventilation if needed. |
| Controls | Digital controller for MVHR. |
| Cooking | Gas oven/hob. |
| Lighting | 100% compact fluorescents |
| Appliances | A-rated fridge/freezer unit, microwave and washing machine. |
| Renewable energy generation system | |
| Strategy for minimising thermal bridges | Thermal bridge modelling was done on all junctions in order to reduce psi-value as close to zero as possible. The highest value ended up being certain window frames to walls (0.087 W/mK). All other junctions were negative or just above zero. Some were fine as they were, others required modelling with strips of Spacetherm-P (a product that weds aerogel to plasterboard). Junctions requiring this were: (1) Loft to party wall, (2) Solid floor to party wall, and (3) External wall to party wall (in vertical plane). |
Building construction
| Storeys | 2 |
|---|---|
| Volume | 167m³ |
| Thermal fabric area | 270 m² |
| Roof description | Bathroom loft: insulation was done using mineral wool to end up with 320mm thick, giving a finished roof u-value of 0.127 W/m2K. There was some mineral wool there already, but not very much we therefore topped it up a fair amount. Main loft: insulation was done using mineral wool to end up with 300mm thick, giving a finished roof u-value of 0.134 W/m2K. In this case, most of the insulation was already there, we just topped it up.Both ceilings were finished with an airtightness membrane (Intello) that was stapled to batons that had been fixed to loft joists through the existing plastered ceiling, and sealed with Orcon-F to solid plastered walls. This entailed cutting through the top of a stud wall between the stairs and bedroom to allow the membrane to pass, which in turn required that the stud wall was reinforced using a wood frame above the stairs. An airtight loft hatch with ladder was installed in one bedroom. |
| Roof U-value | 0.13 W/m² K |
| Walls description | The external-facing walls of the main house were insulated internally using wood fibre boards 80mm thick. These were fixed directly to the solid wall with concrete screws and plastic washers. Insulation was continuous through floor void, which entailed cutting out floorboards and ceiling plasterboard to accommodate it. We decided not to insulate the bathroom walls internally due to limited space. Insulation could have been done with Spacetherm-P, but since the walls already had cavity wall insulation, the low energy savings vs high cost did not seem to make economic sense. An airtight membrane (Intello) was put in front of the wood fibre boards, followed by batons for the service zone, all fixed in place by concrete screws. Naidec double-sided tape had to be used over the drill hole (just after drilling through but just prior to inserting the screw) to ensure airtightness. Outside, the walls were treated with Keim Lotexan to reduce moisture from driven rain. |
| Walls U-value | 0.36 W/m² K |
| Party walls description | Party walls were not insulated. However, the part of the wall within the floor void was exposed and plastered for airtightness reasons. |
| Party walls U-value | 1.52 W/m² K |
| Floor description | The existing solid floor was insulated using extruded polystyrene (Marmox) 20mm thick, laid with tile grout on solid floor, followed by underlay and 8mm laminate.This was one compromise we made to avoid digging up the existing floor. Insulation thickness was dependent on the existing door thresholds. |
| Floor U-value | 1.06 W/m² K |
| Glazed doors description | |
| Glazed doors U-value | - - |
| Opaque doors description | These were not replaced windows and doors had recently been replaced prior to the refurbishment, so given the other work to do, the client understandably did not feel like spending more money on this element. |
| Opaque doors U-value | 1.70 W/m² K uninstalled |
| Windows description | These were not replaced windows and doors had recently been replaced prior to the refurbishment, so given the other work to do, the client understandably did not feel like spending more money on this element. Window reveals were insulated with 20mm wood fibre board, and the airtight membrane was continued over this up to the frame where it was taped to it using airtightness tapes. |
| Windows U-value | 2.65 W/m² K - |
| Windows energy transmittance (G-value) | 65 % |
| Windows light transmittance | - |
| Rooflights description | |
| Rooflights light transmittance | - |
| Rooflights U-value | - |