After some lovely drinks, David and Betty gave us a fascinating tour of the home that they built to replace their previous wooden house, ‘temporarily’ put up in the 1940s. The house brings together a number of features to reduce its energy and water requirements whilst providing a fantastic, comfortable open living space.
The passive design features include the large number of high specification double glazed windows on the south side to maximise ‘solar gain’. The house also uses thick brick and blockwork walls and a concrete raft base to increase the thermal mass of the building, allowing it to resist extreme temperature fluctuations. The walls, floor and roof all use thick insulation as well to minimise heat transfer and the house is essentially air tight.
Ventilation is active with a clever mechanical heat exchange system that gently removes stale air from the house, using it to heat up incoming fresh air. The set up of the unobtrusive vents is also clever. The stale air is extracted from the kitchen and bathroom which generate most moisture so that the has no condensation problems at all. The most amazing feature of this active ventilation system, for me, as that it runs on just 11W of electricity – equivalent to a fluorescent light bulb.
And speaking of lighting…
The Moxons chose an elegant mix of passive and highly efficient electrical lighting. The south facing windows provide a lot of natural light to the main living space and to compliment this, the north facing rooms have been fitted with light tubes that channel natural light form hemispherical domes on the roof to flat diffuser plates set flush with the ceilings. Some compact fluorescent lamps are used to provide light at night but the bulk of the artificial lighting comes from lines of LED spot lights. Consuming just a few Watts of electricity, these are even more energy efficient than the ‘low energy’ fluorescent lamps.
Three renewable energy technologies have been deployed to provide heat for the house. Evacuated tube solar collectors meets about half of the Moxon’s hot water requirements with an immersion heater used to top this up in the winter. The house also boasts a 4kW wood burning stove and a ground source heat pump. The heat pump, basically an inverted fridge, uses just 2kW of electricity to pump fluid through pipes in the garden, extracting then concentrated 8kW of heat which is then fed through a highly effective set of pipes under the floor of the house.
To provide the massive surface area of ground needed to feed the heat pump, the garden is host to hundreds of metres of anti-freeze filled piping. These ‘slinkies’ were was laid out in a spiral pattern along the two 50m long and 2m deep trenches before being burred and the garden surface restored. Whilst the garden may feed the house with heat in the winter, the house feeds the garden with water in the summer. The gutters of the house feed into a 5000L tank, burred in the garden. This tank connects to a number of vegetable beds via pipes and slow drip hoses that ensure a steady, even supply of water when running.
All in all
All in all I came away feeling that the Moxons have succeeded in creating a sustainable home, truly fit for the 21st Century. They also succeeded in creating a light, comfortable and rewarding space to live in.