Hockerton Housing Project

Site – Hockerton England (close to Nottingham)

Project Objectives

• To provide 5 reasonably priced houses to sleep families of up to five close to Nottingham towards meeting the goals of sustainability. The main deign brief for the housing development was -
• Minimum overall environmental impact
• Minimum energy use from the grid
• Conventional space and comfort

Design Philosophy

The design of the accommodation was based on the idea of keeping the construction materials and design complexity down to a minimum. For this reason each house is constructed as six identical bays.

Diagram 1 Diagram 2

Diagram 1 shows the bay construction. Each bay is 3m wide by 6m long. There are 3 bedrooms, a sitting area a kitchen, a hall and a utility room. The sun space or conservatory is a non-heated space and is fully glazed. The glazed roof is 2.3 metres at the front and slopes upwards to 3m high inside. There are two entrances to each room, double glazed doors as well as internal doors.

The site is oriented due south to maximise southern exposure and has a very high degree of thermal mass. The sun space is used to capture heat from the sun; this is then transported into the living spaces. Diagram 2 shows the very high levels of thermal mass due to the earth-sheltered design. The large amount of thermal mass charges during the summer periods and release the energy during the winter period.

Technology

The main technology incorporated into the design is that of passive technology.

• Windows and doors between conservatory and roof are triple glazed, low emissivity and argon filled.
• Conservatory roof is double glazed low emissivity.
• All appliances used in the accommodation are highly efficient according to the EU water/energy efficiency scheme
• Most lighting appliances are compact fluorescent lamps
• Building walls made from 300mm concrete.
• Building fabric insulated with 300mm of thick expanded polystyrene.

Ventilation

The windows on the roof of the conservatory allow adequate natural ventilation during the summer months. Mechanical ventilation heat recovery is used to supply fresh air to the living room and to the bedroom and supplies fresh air to the kitchen and bathroom areas.

Water

The only supply of water used at the site is rainwater; rainwater is collected and stored in a tank for the drinking water supply. Water used for other purposes is stored in a small pond.

Hot water is supplied to each house via an air to water heat pump. The used in the heat pump is positioned at the top of the conservatory in order to gain maximum amount of energy for maximum evaporation. Hot water is stored in a large tank of 1500 litre capacity in the utility room/ laundry room of the house.

The toilets used are low volume water flush models. Waste water is initially treated in a septic tank; the overflow then passes to a large pond with rush mats with phragmites communis reeds growing on the rush mats. Inlet to the pond is at the centre of a baffled arrangement of rush mats. The waste water follows a spiral path through the rush mats before overflowing to a larger pond/small lake. The quality of the water in the small lake exceeds standards set by the EU for bathing and swimming.

How effective is the design ???

The internal temperature during the winter period is found to be 18^oC and 23^oC during the summer months. On a daily basis there is a very small change in the internal temperature; around 0.5 ^oC. The energy use from the grid for each household is around 8 KWhr/day. A large proportion of this is from the electric cooker.

Site impact

The construction of the building cause a significant level of disturbance, however one year after the house were opened the site was fully recovered. The lake is also now attracting new species to the area.

Human comfort

Occupants of the houses seem too happy with the internal temperature and humidity. As the site is adjacent to a busy main road it was essential that there was minimal noise disturbance from the road. The high level of thermal mass resultant from the earth sheltered design means that noise levels from within the house are insignificant.