Working in partnership with Edinburgh Napier University to carry out Part 2 of the evaluation established the energy consumption across the 10 blocks, 25 homes in total over the first 12 months of occupation.
In terms of occupational patterns the following was established:
- 56% of the residents were either unemployed, retired or had a disability.
- 44% of the residents were employed with intermittent occupancy.
- the total average occupants per household was 3.
A summary of the key outcomes are below, however please refer to the full report for details, including the evaluation methodologies used.
- Annual Energy Consumption
- 96% of the homes performed better than the UK energy consumption benchmark.
- 40% of the homes consumed more than the delivered HIS average energy consumption rate.
- The homes using higher levels of electricity consumption either have a higher number of occupants or higher levels of electricity used to provide heating (e.g. ASHP plots 5 & 9) or may have experienced a fault in their controls.
- Annual Carbon Emissions (heating and electricity demand)
- 60% of the homes are below the HIS average carbon emissions rate.
- The highest carbon emitting home is plot 22 at 53kg CO²/m²/yr which is occupied by 2 unemployed adults.
- The lowest carbon emitting home is plot 3 at 17kg CO²/m²/yr which is occupied by 1 adult and 1 child with intermittent occupancy.
- Annual Energy Costs
- Electricity is the predominant energy cost.
- Average HIS annual energy cost is £680 per year which is below the typical Scotland domestic consumption cost of £1,115 (DECC, 2012).
- Heating Costs only
- Flats range from £150 to £480 per year.
- Bungalows range from £180 to £480 per year.
- Terraced 2 Storey Houses range from £225 to £470 per year.
- Properties with an electric ASHP spent more per year compared with gas fueled heating.
- Average HIS heating cost is £312 per year compared to the predicted average cost of £145 per year.
- Heating Consumption
- Performance gap identified between predicted heating energy consumption and actual.
- Actual heating consumption range between 3,300 and 17,300 kWh/yr.
- Average HIS heating consumption is 8,200 kWh/yr which is below the Scottish benchmark of 14,800 kWh/yr.
- Electricity Consumption
- Electrical energy consumption varies significantly between the houses given the diversity of technology, house type and occupancy patterns.
- Properties which use ASHP have been identified as high electrical consumers.
- Actual electricity consumption range between 1,170 and 7,161 kWh/yr.
- Average HIS electricity consumption 3,070 kWh/yr which is below the Scottish mean consumption rate of 4,557 kWh/yr (DECC, 2013).
The results demonstrate a significant shortfall against the predicted consumption. Industry led change is required to reduce the performance gap through enhancing communication and site awareness in the execution of energy efficient methods.
The data presented in this study is for the first 12 months of occupation when tenants were unfamiliar with the systems. The results may not therefore be representative of a typical building performance. The Phase 2 study which is currently underway will provide a more realistic account of building performance.