Our All-Electric Future (collected short essays from 1990s)

Most contemporary offices are 6m deep and 2.75m high and have a 1% Daylight Factor (D/F) at the back giving say 50 lux on an overcast day and strong contrast with the window wall. Is it surprising that the electric light, say 30 w/sqm and 90wh/sqm, is on for 8000 hrs per year? This equates to about 150kg CO2/sqm/yr and a large electricity bill!. Lazy property management is still an issue.
Design for a minimum D/F of 5% at the back of the office, achieved with the window wall of height closer to the depth of the office, or the use of holographic film or light reflecting shelves to direct the light to the rear of the space. As the design light level increases the area of glass has to increase. During periods when no light is available the glass should be insulated with quilted blinds or automated shutters.

As the outside temperature rises and the sun shines more often heat has to be rejected from the building. Traditionally people do this by opening windows. About half the glazed area should be openable. 50 to 100 air changes per hour creates comforting breezes for temperatures in the low 30sC. Opening windows in the summer (provided that dust and noise are not obstructions) is logical and sensible. Mechanically CO2 level-controlled winter ventilation, with heat recovery, is sensible.

The winter heat gain is intermittent, and it has to be integrated and smoothed over the day by a building of adequate thermal mass. The thermal mass integrates the heat gain in summer so that surplus heat can be rejected at night and prevented from causing overheating in the day.
Only for very hot climates is refrigeration needed. Even then, good design can eliminate this. With the measures for conservation suggested here the heat gain is very small and the electricity from renewable sources should be integrated to cope.

We are besotted with Carbon Emissions when the reality is the consumption of kWhrs for the life of a building. Many kWhrs can be offset in existing buildings for good by the addition of efficient insulation (though difficult to do – practically, and there is insufficient industrial capability), solar water panels, or a green energy tariff, etc. With new buildings this can be achieved without much design effort.

The consumption of kWhrs / annum is and will remain the measure that everyone can understand. It is this that produces the carbon figure.

It is the electricity meter that measures the behaviour of its occupants.