Heating, domestic hot water, ventilation and electrical installations all aim to minimise energy consumption without reducing control. This has been achieved by integrating the services' design with the building fabric, using energy-efficient technology and taking advantage of the system's sophisticated controls.
Water is becoming a very important resource. Attention has therefore been paid to reducing potable water consumption in and around the house. The use of rainwater, recycling grey water and low-water-consumption outlets within the house have all been included.
Even the white goods do their part to minimise energy and water consumption. The fridge uses just 30 W, less than a light bulb, and the washing machine, tumble dryer and dishwasher all use around half the energy and water of standard machines.
Heating
Because of the very high insulation levels used in the building fabric, very little heating is actually required. However, the Integer house has not been designed as a no-heating house, so some heat must be provided, as efficiently as possible.
Floor-mounted trench heaters, supplied by hot water at 50ºC, deliver heat to the living spaces. For individual temperature control, each room has its own thermostat connected to a manifold, from which hot water is distributed around the house. This system means that heat is only delivered to those rooms that actually require it.
The lightweight, highly insulated nature of the house means that it responds rapidly to changes in heat input. The heating system has therefore been designed to have similar fast response characteristics. This ensures the house does not overheat and maintains a high level of comfort for the occupants.
The SeaChange controls, including the room thermostat controls, use fuzzy logic to optimise system efficiency and provide a high level of flexibility. As well as being able to control each room separately, the controls will calculate the best time to switch the heating on to warm the house to the desired temperature. Despite being sophisticated, the controls remain simple to use with the same temperature and time functions as a conventional controller. The more advanced functions are all handled automatically, providing benefit to the occupants without more work.
Heat pump
There is no conventional boiler in the Integer house. Instead, heat is supplied by a heat pump. This acts like a fridge in reverse, taking energy from a cool source and delivering it at a higher temperature to a warm sink. In this case, the cool energy source is the ground and the warm energy sink is the hot water used to heat the house. Although heat pumps use electricity to drive a compressor, they are very efficient, providing around three units of heat to the house for every unit of electricity consumed.
The ground is used as an energy source for the heat pump because it remains at a relatively high temperature in the winter, compared to other possible sources, such as air. To access the ground, two 50 m-deep bore holes have been sunk by GeoScience and a sealed water loop buried in the ground. Water is pumped round this loop, picking up energy from the ground and delivering it to the heat pump before returning it to the ground to repeat the cycle. The SeaChange controls are linked to the heat pump to ensure that it only runs when there is a demand for heat in the building.
Solar water heating
Even though the Integer house is located in the UK, a large part of its domestic hot water heating requirement is met by the sun. Obviously there will be summer days when solar energy provides all the hot water, but on bright, clear days in winter, the system will also provide some water.
The Integer house uses a Thermomax evacuated tube system to collect energy from the sun. This system is highly efficient and can supply water at more than 100ºC on sunny days. However, in domestic applications, the unit is set to restrict water temperatures to 95ºC to avoid boiling.
Water is pumped from the solar collector on the roof to a highly insulated thermal store within the house. The thermal store is maintained at 77ºC and enables energy from the sun to be stored for use when hot water is required. The temperature of the solar collector and the thermal store are both monitored. A control unit uses this information to restrict pump operation to occasions when a net energy benefit can be achieved.
The thermal store is based on the Gledhill PulsaCoil and uses immersion coils to provide backup for those times when the solar power is unable to provide sufficient heat.
When hot water is required at a tap, the thermal store gives up some of its energy to the mains pressure hot water circuit.
By delivering hot water directly from the mains supply, a good pressure is always available at the tap and there is no need to provide storage space in the roof.
Ventilation
It is important to ensure there is adequate ventilation, both to provide occupants with fresh air and to remove moisture and odours from kitchens and bathrooms.
A Willan fan-assisted passive stack ventilation system has been chosen as the means of providing ventilation for the Integer house.
Air is drawn out of bathrooms and kitchens, using natural driving forces caused by temperature differences. Replacement fresh air enters the living rooms via trickle vents in the windows and then flows into the kitchen and bathroom. The continuously low flow rates mean that there are no uncomfortable draughts.
Automatic humidity controls in each extract grill increase the ventilation rate at times of high moisture production, such as when cooking or taking a shower.
A fan provides a back up, enabling boosted ventilation rates if required. In order to avoid energy consumption, this fan uses electrical power supplied by a Rutland 960 wind generator and two 60 W Solarex solar panels. By using two different sources, a more even power supply is provided.
However, as with all such systems, power is not always generated when it is required. Therefore a 200 Ah battery store is kept charged by the wind generator and solar panels. The battery store then drives the ventilation fan through an inverter.
Grey water recycling
Only about 5% of the water supplied to homes is used for drinking and food preparation. The remaining 95% is used for toilet flushing, cleaning and irrigation and does not need to be of the same high quality. The economic and environmental cost of supplying all water used to potable standards is high and unnecessary. The Integer house recycles water used for washing and bathing – grey water – and uses it for toilet flushing. In this way, a reduction in potable water usage of around 30% can be achieved.
Grey water is collected from the bath, showers and handbasins rather than going directly to the sewer system. This water is filtered and biologically treated by the Anglian Water two-stage process to remove soap, dirt and bacteria. The treatment plant is buried in the garden, avoiding any unsightly equipment around the house.
The treated water is then delivered to a storage tank in the roof space and used for toilet flushing. When insufficient grey water is produced, mains potable water provides a back-up supply to the storage tank. Any excess of grey water overflows from the treatment tanks into the mains sewer.
Automatic garden watering
An automatic rainwater collection and distribution system has been installed as part of the water efficiency measures.
The keen gardener uses substantial amounts of water in the garden during the summer months. As with many other uses of water around the home, water for the garden does not need to be of drinkable quality. In fact, if rain fell evenly throughout the year, there would probably be no need to water gardens at all. A rain water collection vessel has therefore been buried in the garden at the Integer house to collect excess water from the conservatory roof in the winter for use in the summer. This storage tank is substantially bigger than the average water butt to ensure that water is available, even through extended periods of hot weather.
The rainwater store is linked to a Hozelock automatic watering system for the conservatory and parts of the garden. A network of pipes deliver water directly to the plants requiring water. Soil humidity is used to control water flow, delivering the correct amount of water at the correct time.
With around 50% of the energy consumption and less than 7O% of the water consumption of a conventional house, Integer is leading the way in conserving resources without compromising comfort.
Source
Building Homes
