'Study nature, love nature, stay close to nature. It will never fail you.'
Frank Lloyd Wright

Solar hemicycle residences near Claverdon village, Warwickshire

SUMMARY: Three contemporary near energy self-sufficient residences in a rural area of Warwickshire. Planning Permission was granted in Spring 2005, and construction took place (not under Carden King direction) in 2007/8.

The scheme is located in Greenbelt and in a Special Landscape Area. Development was predicated upon the replacement of existing derelict industrial buildings on the site (together with a considerable area of hardstanding) with three low-profile eco-friendly residences. Planning Officers supported the scheme throughout on this basis, though the scheme had to go to Appeal - which it won.

All three residences were completed by a local developer who purchased the site and the Planning Permission from our original client.

DETAIL: The term 'solar hemicycle' refers to a shape of a house (or other structure) and its purpose. 'hemicycle' comes from the shape of the structure being part of a circle, and 'solar' refers to the use of passive solar gain (greenhouse effect) to generate the majority of heat inputs. The solar hemicycle house type was 'invented' by the American architect Frank Lloyd Wright with the design of the second Jacobs residence in Middleton, Wisconsin, in 1944.

The concave solar hemicycle plan form gives these houses a large area of south-facing glass for the generation of heat through passive solar gain, while presenting a highly insulated roof and masonry walls to the North. They are in a sense 'solar generators', designed specifically to harvest the radiated heat of the sun itself. They are oriented specifically for this purpose with their glazed walls facing just West of South. One useful characteristic of the concave hmicycle form is the formation of a courtyard to the South of the structure.

These residences are quite large - the client's brief called for five bedrooms (three doubles with ensuite facilities) together with two separate lounges. The total heated floor area is approx. 313 square metres. There are three residences within a site of approx 1.6 Hectares in area. Much of the site outside the circles of the houses is to be planted to match local low scrub and woodland, and maintained as a nature reserve for the residents.

Overheating is a real danger with houses majoring on passive solar gain. This design was to incorporate vertical metal mesh roller blinds externally to provide shade on the hottest summer days, the housing for these being in the second floor eaves and in a continuous leaded ledge at first floor level. Other natural cooling aids included a deep second floor roof overhang, cross ventilation, high thermal capacity, the possibility of a pool drawn up to the house on the Southern elevation, and low-level ground-cooled air inlets to provide additional natural air conditioning. On the very hottest days the heat pump would be capable running in reverse to provide cooled air if necessary. It was envisaged that these houses would rely entirely on natural cooling methods.

The heating system was envisaged to utilise the heat created by solar gain and other heat sources within the house together to heat water via an air-source heat pump located in the loft over the carport. Under this arrangement all of the heat produced in the house including that produced by solar gain, cooking, lighting, etc. rises via gravity to second floor ceiling level where it is extracted to feed the heat pump. The ground floor ceiling was to taper upwards towards floor slots adjoining the South window/wall to encourage warmed air to rise. The water heated by the heat pump was to be contained in super-insulated tanks in the carport loft and utilised for underfloor heating and domestic hot water. Surplus warmed air would be exhausted via ridge vents on warm/hot summer days. An option available to residents - shown on the perspective views here - is for two tracking solar photovoltaic arrays located at the southern gables of the house. These solar arrays can be used to help power the heat pump or to send electricity back into the grid.

All masonry elements and floors were to be heavy construction to give the residences medium to high thermal capacity.

For Planning purposes the residences were cut into the sloping ground by up to 1.5 metres. This created a sunken garden immediately to the South of each house, bounded by a low wall which defines and contains the inner gardens.

Materials for the residences were to be reclaimed brick, hand-made red plain clay tiles and FSC (Forestry Stewardship Council) sourced timber. As many local materials were to be employed as possible and the concrete hardstandings and roadway foundations previously on site were to be broken up for hardcore in order to reduce/eliminate the export of spoil from the site. The Ecohomes rating for these residences was 'very good'. We were unable to achieve the highest category on account of the lack of shops and bus routes in the vicinity of the site.

Statistics:

-         Radii of outer circle: 15.500 metres

-        Gross Internal heated Floor Areas:

     -        Ground Floor: 197 square metres.

     -        First Floor: 116 square metres.

-       Total Gross Internal heated Floor Area: 313 square metres.

-         Number of bedrooms - 5.

-         Number of bathrooms - 4.

-         Approx. area of PV panels shown - 18 sq m. (2 no. 3m x 3m tracking arrays).

-         Approx. area of South-facing glazing (45 deg each side of South) - 74 sq. m.

-         Area of North-facing glazing (45 deg each side of North) - 10 sq.m.

-    This design can be realised on a site with clear Southern exposure of an area of approximately half and acre, which is approx. 45x40 metres (148x131 ft.) in area.

 

Aerial view from Southwest. The garden courtyard formed by the concave hemicycle form is clearly visible here.
Ground Floor plan. The pure form of the hemicycle itself is intersected by a 'polliwog tail' at right angles. The 'tail' contains a large carport, Utility room, WC, recycling storage, bicycle store, and a staircase to the first floor over the carport.
First Floor plan.The first Floor plan is focussed on the interior courtyard garden, though each room derives light and cross ventilation from rooflights to the rear also.
Aerial view from South.
Construction photograph - from Southeast.
Southeast gable detail. This view gives these houses a distinctly vernacular look. While the plan looks alarming, the perspective views look almost normal.
Image of a completed residence from Southeast. Detailing and site supervision was not carried out under the direction of Carden King.
Balcony and Dining area - detail. Some of the Dining 'bubble' doors were to open, and the pool intended to help cool the interior by slightly cooling breezes that pass over it.
Construction photograph - internal, First Floor.
Construction photograph - from North.
Image of the interior of a completed residence. The interiors were simple and contemporary, but were not executed under Carden King's direction.
North wing and Entrance Court detail. The planters and all of the walls that extend from the house are intended to anchor it to the landscape.
Entrance Area detail. A diagonal wall of local fieldstone marks the entrance. The 'vase' at the top is formed from an upturned circular plough harrow disk.
North wing detail