Heating demands are limited by having high standards of insulation, building air-tightness, and by controlling ventilation. Additionally, the main space takes advantage of south-facing glazing, with shading specifically designed to admit winter sun. The combined effect is to reduce heating demands to 50 per cent of those of a typical building.
The heat source for the building is a ground-source heat pump. A geothermal heat exchanger forms part of the system and comprises six 'U' loop pipes sunk 80m deep into the ground. Water flows from the heat pump into the geothermal heat exchanger at about 5infinityC and returns from the ground 2infinityC warmer. This is a form of solar heating, since it was the sun in the previous summer that warmed the earth surrounding the RSPB building either directly or by the movement of ground water. The heat pump absorbs the heat from the geothermal heat exchanger and passes it to a secondary circuit. At the same time the heat pump imparts a thermodynamic compression process to elevate the temperature of the water in the secondary circuit to 35infinityC. The secondary circuit distributes heat throughout the building using underfloor heating. Underfloor heating is specifically chosen to complement the ground-source heat pump which operates at optimum efficiency when producing water at a warm temperature (35infinityC). Thus heating is achieved by having, inside the rooms, a large, warm object (the floor at 35infinityC) rather than a small, hot object such as a radiator at 50infinityC or an open fire at 500infinityC. The combined effect of limiting the heat demands and the ground-source heat pump scheme means that the CO 2 emissions associated with heating energy demands are 75 per cent lower than those of a typical building. Roof-mounted photovoltaics generate electricity from sunlight and, when installed, the proposed wind turbine will generate electricity when the wind blows. The combined effect of these two renewable-energy generators is predicted to make the building carbon neutral.
NATURAL VENTILATION TERMINAL DESIGN ENSURES WIND-DRIVEN VENTILATION COMPLEMENTS BUOYANCY-DRIVEN VENTILATION UNDERFLOOR HEATING HAS LARGE AREA.
THIS ALLOWS LOW-GRADE HEAT TO BE SUFFICIENT TO MEET HEATING DEMANDS AND THE HEAT PUMP TO OPERATE AT MAXIMUM EFFICIENCY HIGHEST-EFFICIENCY LIGHTING WITH DAYLIGHTSENSED DIMMING MINIMISES LIGHTING USE AND COOLING RAINWATER IS COLLECTED FROM THE ROOF, STORED BELOW GROUND AND THEN USED TO FLUSH WCS. TOTAL WATER SAVED IS 130 TONNES/YEAR GROUND-SOURCE HEAT PUMP PROVIDES SPACE AND WATER HEATING. HEAT IS EXTRACTED FROM THE GROUND. THE HEAT PUMP USES A THERMODYNAMIC PROCESS TO ELEVATE THE TEMPERATURE OF THIS HEAT FOR USE IN THE BUILDING.
THE HEAT PUMP REQUIRES ELECTRICITY TO RUN. FOR 1 UNIT OF ELECTRICITY CONSUMED BY THE HEAT PUMP 4 UNITS OF HEAT ARE DELIVERED.
TOTAL HEAT PUMP DEMAND: 8MWHRS/YR.
HEAT PUMP CARBON INTENSITY 0.11KGCO 2/KWHR COMPARE TO GAS HEATING 0.26KGCO 2/KWHR COMPARE TO ELECTRIC HEATING 0.33KGCO 2/KWHR ELECTRICITY GENERATED BY PHOTOVOLTAIC PANELS. YIELD 10 MW HRS/YR. TOTAL BUILDING ENERGY DEMAND 40MW HRS/YR SUMMER SUN IS OCCLUDED BY LOUVRED BRISE SOLEIL WINTER SUN IS ADMITTED BY LOUVRED BRISE SOLEIL AUTOMATIC VENTS IMPLEMENT SUMMER NIGHT COOLING. HIGH THERMAL CAPACITY STRUCTURE USED TO RETAIN COOLTH