| Planned occupancy | This property is part of the social housing stock managed by L&Q Housing Association and is currently occupied by a family. The tenant will remain in-situ for most of the construction, and we will minimise and group any work that will require the tenants to be relocated temporarily. The work flow will be designed to be of least inconvenience to them. |
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| Space heating strategy | For space heating energy demand, Green Structures has developed an upgraded passive solar thermal system which warms air by combining powerful solar thermal collectors, a 90%-efficient heat exchange system and a specially developed Phase Change Material (PCM) thermal mass accumulator. The PCM heat accumulator has been developed to collect any excess heat and store it for instant use at any given time, specially during the winter season. |
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| Water heating strategy | The hot water heating will be provided by an unvented hot water cylinder heated by solar collectors and combined with Phase Change Material (PCM) storage. The domestic hot water demand will be easily met without the usual volume/speed compromise associated with solar thermal hot water heating. |
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| Fuel strategy | As the majority of water and space heating will be provided by solar thermal, mains gas will be disconnected from the house, and only a small amount of electricity will be drawn from the grid.The adaptive home monitoring and control system will balance the needs of the occupants with the needs for energy efficiency. |
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| Renewable energy strategy | We have chosen not to use photovoltaic cells as this is the least cost-effective solution for energy production. We will be using instead passive solar thermal collectors, which are over 80% efficient, as opposed to most photovoltaic cells, which are only 15-20% efficient. |
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| Passive Solar strategy | In addition to the 80% efficient passive solar thermal flat plate collectors which we have oriented South, we will be replacing the existing windows with PassivHaus standard windows and argon-filled, double-glazed windows to obtain passive solar gains. |
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| Space cooling strategy | The insulated thermal mass of the envelope in conjunction with the loft area act as a buffer for the building volume by preventing any overheating. Also, in summer all the windows can be fully opened to induce cross ventilation. The adaptive home monitoring system will be capable of measuring the internal temperature and ensuring adequate ventilation. |
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| Daylighting strategy | The average daylight factors of the proposed retrofit scheme will not alter or reduce the current daylight factors of the existing dwelling. |
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| Ventilation strategy | Full House Heat Recovery Ventilation System with 92% efficiency. Supply Air ducted to Bedrooms and Living Room, Extract from Kitchen and Bathrooms. System is to be combined with our Passive Solar Space Heating System. |
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| Airtightness strategy | Insulation wrapping of external walls, floors, footings and roof spaces. All windows will be replaced with airtight PassivHaus standard windows. Contractors will be specifically trained in airtight construction, with constant onsite cross-checking and supervision to ensure airtightness. Airtightness will be designed from the outset into the retrofit scheme. Accurate detailing at critical points will be covered on the drawings. |
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| Strategy for minimising thermal bridges | Full continuous insulation of external walls, floors, footings and roof spaces, with overlapping/wrapping of insulation at junctions with potential thermal bridge, e.g. overlapping of wall insulation over window and door frames, wrapping of wall insulation over corner of rooms and eaves, new window sills attached to external insulation instead of the wall. Existing thermal bridges will be designed to be eliminated at the design stage or they will be isolated where they cannot be prevented. |
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| Modelling strategy | Whole house modelling was undertaken in PHPP and verified with SAP2005 Extension for Whole House. |
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| Insulation strategy | 120mm Phenolic external Solid Wall Insulation to the rear of property, and 100mm Phenolic internal insulation to the front. Wall insulation is to be combined with below DPC waterproof insulation as well as new roof insulation. |
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| Other relevant retrofit strategies | The aim of the project is to create a cost effective and comprehensive solution that can be up-scaled and applied throughout the UK social housing stock. We have achieved this through developing effective processes, efficient systems and designing in future economies of scale, e.g. by forming teams of highly trained Retrofitters equipped with modular and accurately matched Retrofit Packages we could reduce future process costs by up to 50%. From previous experience, we understand the importance of engaging the tenants and establishing a working relationship throughout the process. We will keep the tenants well informed and they will be consulted on proposed changes to their homes. |
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| Contextual information | We have selected products and technologies based on their future potential cost related to economies of scale and not to current cost. This does inflate the current cost of the Retrofit and makes the targets even more challenging but it provides the greatest future cost saving potential. Also, the inclusion of smart grid Thermal Accumulator technology will potentially allow householders to earn money by storing excess grid capacity as high grade heat during periods of high wind and therefore offsetting upfront costs. In addition to energy saving measures and renewable energy production, the retrofit is designed to provide a high level of comfort, minimise disruption for the occupant, and keep the aesthetic integrity of the existing home. |
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