Little House Kendal - First Certified Passive House In South Lakeland Cumbria Client Information for UK Passive House Trust Award 2016 Design Statement 1. To build a beautiful and practical, energy efficient four bedroom family home, with built in adaptability for disabled downstairs living if necessary in the future, reflecting the style preference of the clients. 2. The cost of the build and the land should not exceed the market value of the property on completion. 3. As an infill development it needs to complement the existing styles of properties in the immediate vicinity, which are varied but very traditional in design. This led to the requirement that the design make use of local stone, have a slate roof and also have a non-uniform profile, and the site be excavated to a depth of approximately 1.8m. 4. To make best use of the benefits of this site, including an excellent south facing exposure and superb views to distant hills. 5. Take advantage of using Passive House Criteria to ensure the house built will perform as designed. 6. To use local expertise, trades and materials wherever possible in order to minimize carbon footprint and to support and buy into the local economy. 7. Construction method to be tolerant of Cumbrian weather both during construction and over the lifetime of the house. Air Tightness results ac/hr@50 pa ( +/- 0.05 tolerance) Initial 0.11 (15th June 2015) Middle 0.17 (18th August 2015) Final 0.20 ( 3rd December 2015) Measured Energy Performance and internal data. Please see the table below. Internal temperatures are measured on the landing. Living room approximately 1.5 degrees higher. Energy values are quoted from the Worcester Bosch Wave device which compares well with our gas meter readings. Carbon dioxide values quoted are calibrated so that 400ppm is equivalent to outside concentrations on this device. PV Generation reading, we have generated 1167 kWh in total and we have used and paid for 1559 kWh according to our electricity meter. However quite a proportion of that was used by the builders before we moved in. Unfortunately we do not have any break down of these figures. Solar Iboost. We have used 252 kWh generated from PV in total to heat water with this device of which 121 kWh was used in the last month! Data is limited to when we moved in to the house and started taking readings in Dec 2015. More data will be recorded in time. Space heating data Outdoor Indoor Month (PHPP) Monthly Method Specific Heating for Predicted Energy ( Bosh Worcs Wave device) Energy recorded Actual Heating site) (Recorded temp Outdoor on DailyAverage Maximum (Recorded temp on site) Daily Outdoor Average Minimum range Daily temperature Outdoor Average Outdoor humidity. daily maximum Average indoor maximum temperature. daily Average indoor minimum daily Average temperature. range IndoorAverage Daily temperature indoor CO2 daily reading Average indoor maximum Humidity daily Average indoor Humidity daily Average Comment KWhr (+/- KWhr 20KWhr) °C °C °C % °C °C °C ppm % % Dec-15 413 400 No data available Jan-16 404 440 12 4 8 98 20 17 3 523 57 Feb-16 279 360 9 0 9 95 19 16 3 540 53 Mar-16 200 200 11 2 9 92 20 17 3 531 50 Apr-16 89 40 12 4 8 89 20 18 2 506 49 Occupancy Feedback It’s really quiet. The only thing you notice about outside is when it is sunny. We are completely unaware of rain wind or the temperature. However, because of the large windows and the excellent light quality in the rooms we actually feel like we are living outside and the kitchen and living room floors appear to continue without a break into the lawn. The house temperature remains more or less constant. However, our perception of temperature depends on how active we are. We cannot easily change the temperature of the house to suit our moment to moment perceptions and therefore need to control our personal environment (a light sweater will usually do it) rather than our surroundings as we might be tempted to in a more traditional house. We have also had to get used to sleeping in the equivalent summer conditions throughout the winter. No dust, no spiders, no irritating fans in bathrooms waking the house up, towels dry quickly on towel rails that are hardly ever on. Fantastic air quality means our teenage son’s smells are rapidly extracted. The heat recovery showers are luxurious and efficient and a pleasure to use simultaneously. Getting the post from the garage (outside the thermal envelope) is bit of a pain. Statement of Design Intent Local experience favored using a pre-assembled timber frame to ensure insulation was kept dry and key features such as airtightness and lack of thermal bridging was achieved to a consistently high standard. This also allowed the vulnerable construction to be completed quickly (48hrs) during a short spell of good weather (Cumbria). This was possible because of the expertise of a local manufacturer of high precision timber frames. The most cost effective choice for the façade then became rendered blockwork, which is also one of the most common forms of local building techniques, nearly always combined with natural stone. Hence the use of stone to build the front porch and the garage (outside the thermal envelope) which were designed to make the external shape of the building less uniform. Internal downstairs blockwork walls and an insulated concrete raft for thermal mass (to provide a heat reservoir in winter and cool in the summer), while upstairs light weight construction of the bedroom walls was used to allow night time window opening without the loss of too much heat. Solar shading on large south facing triple glazed windows (required for solar gain) has been provided unobtrusively by the use of recessed windows a large roof overhang and a veranda over the patio doors. Anodized aluminum exterior window frames were used for weather resistance. Cost and Buildability (including attached garage, porch and landscaping works ) 1. Substructures: Ground Works Reduced Level Dig Excavations, Retaining Walls. Foundations, Site Works / Driveway / Gabion Walls / Fencing . Drainage Foul & Surface Water (above & below ground). Incoming Services / Water / Electric, Gas & BT ground work, garden landscaping etc. Internal Walls and Partitions , Concrete Blockwork & Internal Doors £70,151 2. Timber Frame / Upper floors / Walls & Roof £72,654 3. Windows & External Doors £21,877 4. Stairs £1,136 5. External Walls Render , Wall & Ceiling Finishes / Plaster Board & Skim £16,000 6. Floor Finishes / Carpet / Tile / Wood and tiling in shower rooms. £16,516 7. Finishes Decorations £6,500 8. Kitchen & Utility Units £15,000 9. Sanitary Appliances £3,732 10. Fittings & Furnishings Wardrobes Cupboards £3,468 11. Mechanical & Electrical Plumbing / Electrics / Ventilation (including labour) £42,621 12. Incoming Services / Water / Electric, Gas & BT connection charge £3,665 13. Miscellaneous labour re above items £72,169 Labour & Materials Total: £345,489. This includes the landscaping of the back garden which I estimate it is about £10,000 (an underestimate if anything). This would make the build cost £335,489. I also estimate there is about £15,000 due back on VAT reclaim. We have calculated the Garage & Open rear porch outside the thermal envelop cost £41,000K This would put the actual Pasivhaus thermal envelop at £279,489 TFA = 115m2 so cost sqm = £ 2,430.33 sqm The QS report gave a cost value of £415,606 of which £81,185 was preliminaries and contingency. The contingency was not needed and the preliminaries were unnecessary since we did not use a main contractor. We therefore came in pretty much on expected cost for the build but saved a lot by self building with directly employed local sub-contractors. We commissioned a QS report at the start of the project and this was invaluable. The total cost of the build came in exactly on the QS report, once the contingency and administration costs were removed. We made a choice to accept a higher degree of risk by not putting the project out to tender and using a local builder who we paid by the hour, he then advised us on choice of separate sub contract trades. We also employed an experience passive house M&E engineer, Alan Clarke, this ensured that we did not over specify and easily saved the cost of paying his fees. This procurement method led to a greater hands on involvement and opportunities to modify the fitting out of the house. One compromise we made was to not put a wood burning stove into the lounge, since putting the flue in was proving to be very difficult and was holding up other trades and therefore having cost implications. Advice from other passive house owners in the area was also invaluable in making this and other decisions as we went along. To some extent the design evolved as we discovered and made use of local products and skills. For example the landscaping of the garden and slate window sills in the bathrooms. Strictly keeping records of every penny we spent ensured we did not over spend and where necessary we choose to spend more on the structural elements and less on fixtures and fittings to stay in budget. Servicing strategy Mechanical ventilation with heat recovery is provided by a Paul Novus 300 installed in the garage, this is adjacent to the thermal envelope to minimize the length of warm ducts in the cold space. Rigid steel ductwork runs within the ground floor, and duct routes were co-ordinated with the floor joist at design stage. On the first floor ducts run in a lowered ceiling void over landing and bathrooms which also accommodates LED downlights.