With mechanical ventilation

In this case the cooling potential of night-time air is optimized by being forced through the building fabric by fans. At the same time it assists in expelling warm air during the day. The system has the advantage that it eliminates the need to have open windows either day or night. It also offers control over the supply and extract air flow.

Figure 3.9 Enhanced surface heat transfer system (courtesy of BRE)

A variation is described as the 'enhanced surface heat transfer system'. A perforated metal sheet is applied to the underside of the floor slab leaving an air gap. Air is mechanically forced into the gap, creating turbulent air currents which appreciably improve the heat transfer between the air and the slab, maximizing night-time cooling. The external air can be ducted directly to the gap or emitted into the room and then recirculated through the ceiling gap. As with natural ventilation the night-time temperature should be below 20°C. However, the heat gains that can be accommodated can increase to 50 W/m2 (see Fig. 3.9).

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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