Hockerton’s electricity goes carbon neutral! By the end of November the community owned turbine had produced 221 220 kWh which roughly equals the electrical consumption of the village in a whole year. Looked at another way, Sustainable Hockerton Limited (SHL) have saved the emission of 125 tonnes of carbon dioxide into the atmosphere. The impact is small on a national scale but massive on a local one! Congratulations to all concerned!
The tenants of one house have now been back in their home for 2 weeks, and we’ve taken a look at their energy use over that period.
Their total energy consumption is averaging at 11.93kWh/day. At that rate, their annual consumption will be 4,356kWh. However, the heaters are on at the moment – averaging 2.27kWh/day (pretty low!) – so we’re hoping the annual use will be lower than this, as these will not be on all year. It will also probably require more heating this winter as the house has been a building site for 6 months, and not able to build up a store of solar energy from the summer.
So how does this compare to their previous energy use? Well, looking at 18 months of bills prior to the retrofit, they were averaging 3,241kWh/yr of electricity and 18,972kWh/yr of gas.
So down from an annual energy consumption of 22,213kWh to 4,356kWh – not a bad start; long may it continue …
We have now completed the retrofit of the houses, and hopefully you’ll agree they’re looking great.
The existing tenants of number 30, Mr & Mrs Morton, have already moved back in and are enjoying their new home. Newark and Sherwood Homes are advertising for tenants for number 28, which was previously void.
The houses will now be monitored for 2 years to see how they really perform. The monitoring includes:
- Temperature and relative humidity in 3 rooms of the house (sitting room, bedroom 1 & bedroom 2)
- External temperature
- CO2 level in the sitting room
- Total water and electricity consumption
- Electricity consumption on 8 individual sub-circuits
All this data is being monitored automatically and transmitted to a central database at 5 minute intervals, and we can view it real-time via a website.
We are also hoping to do additional monitoring on the properties, and are in discussion with a couple of universities about the possibiliity of collaborating on this.
We hope you’ve enjoyed our blog so far, and watch this space for more news of post occupancy evaluation …
The generally recommeded level of loft insulation, and that provided in most new build houses today, is 250-300mm. The houses already had about 250mm of insulation in the loft, but we have topped that up to between 600-700mm. In addition, we have then sealed the loft hatch so that occupants cannot then compact the insulation by storing lots of belongings on top of it; if loft insulation is compacted, a lot of the benefit of the insulation is lost – it restricts heat transfer because of the air pockets within the fibres.
Although there is no access to the loft, the houses now additional storage areas in the sun space and porch.
The hot water in the houses is provided by a super-insulated thermal store heated with an electric immersion heater. A thermal store is like a traditional hot water cylinder, but the key difference is that the hot water in the cylinder is not the hot water used, instead it simply acts as a heat storage mechanism, hence the term thermal store. The hot water delivered to taps and showers, is actually cold water directly from the mains supply, which is then passed through a large copper coil (heat exchanger) within the thermal store, and in doing so extracts energy from the hot water in the store to heat it. As the water in the cylinder is not being used directly, it does not need to be heated to 60 degrees to kill legionella bacteria; instead it can be kept at aorund 45 degrees, significantly reducing energy consumption. The hot water delivered is around 40 degrees, more than adequate for washing and showering.