Solar Collector: Using passive devices which enhance its architecture, this house manages to reduce energy consumption to a third of the norm.

This solar house manages considerable energy saving through passive means without excessive costs or gadgetry. Essentially linear in concept, it was pushed to the north edge of the site. A string of rooms faces the sun, with a toplit hail behind to the north, and an acoustic buffer of storage cupboards in between. This element does not run full height but is glazed at the top to maintain visual continuity. The main energy device is a continuous glazed balcony tucked under the projecting roof, which acts as solar collector in winter and climatic buffer in summer. Slightly less than half glazed, with standard doors one, two, or three to a room, the massive concrete wall stores heat. Daytime build-up of radiation in winter can be used later. Shaded in the summer, it cools by absorbing daytime heat then losing it at night. Family members can individually adjust the climate of each room by opening and closing the glazed door or vent to exchange air with the buffer.

On a seasonal scale, the buffer's performance is adjusted by two more drastic measures: alternate glass panels slide open to allow full ventilation in the hot season, and the open timber slatted deck can be covered with rubber mats in winter to make the space relatively airtight. The overhanging roof projects enough to keep out midsummer sun. Falling back to the north, it slopes gently to a gutter at the eaves. The back wall extends the lightweight vocabulary of the roof with timber frame, thick insulation and metal skin. It is blind but for a horizontal slot window in the living room.

If the site were flat and the ends were treated in the same way, the linearity of the house would be oppressive, but the land slopes from the entrance by nearly two storeys, allowing the inclusion of a lower floor for children's bedrooms, utility and study. And the facades could scarcely be more different. The east sets a defensive concrete face to the street, formal and parapeted to conceal the sloping roof section, with a sli t window only onto the buffer. The west, by contrast, is as transparent as possible, its two-storey glazing and generous balconies enjoying wonderful views across the valley. The linear hall-space on which the entrance opens is dominated by the running stair, the passage through the piano nobile becoming a landing and side-stepping to accommodate it. This landing opens to the kitchen and dining spaces, but sliding screens can be pulled across for privacy. The spatial sequence of the house culminates naturally in a room which takes the whole width of plan. You know you have arrived, with views in three directions. There is a hearth in the form of a wood-burning stove, and the spiral stair drops to the study below. The sequence has a dramatic and inspiring form, making the most of the linear plan rather than being cramped by it.

Contrast between light and heavy construction has partly to do with where heat is stored, but also with architectural presentation as with the formal concrete front. Wondra has in places devised ingenious details such as the glass door canopy and the loose-fit stainless steel outer door which allows secure ventilation while the inner one is open. There are cleverly minimal sliding doors, an ingenious shaft to drop dirty washing from the bedroom to a basement cupboard, and glazing over the cupboards which slides in ceiling slots to absorb roof deflections through snow load. But these things are incidental: the virtue of the house is that energy consumption has been cut to about a third of the current norm, yet the architecture is enhanced rather than compromised. The pay-back period for the buffer and insulation is relatively short, and the energy policy involves neither an elaborate technical system nor complex engagement by the user.

RELATED ARTICLE: 1 East (Street) front is massive and impassive.

2 Upper level has continuous glass-fronted balcony on south side to act as climatic buffer.

3 Buffer breathes through floor, which can be made almost impervious in winter with rubber mats.

4 From entrance hall with stair down to children's rooms and study. Gallery at entrance level ...

5 ... leads to living room at west end of house.