The external environment

• Solar shading

• Evaporative cooling.

The orientation of a property can have a significant impact on the extent to which it is adversely affected by wind. This can create a pressure difference between the faces of a building: positive on the windward side and negative on the lee face. This means that cold air tends to be forced into the windward elevation and warmth sucked out of the lee side (Figure 8.12).

The UK has one of the most turbulent climates in Europe. In the UK the average wind speed for 10 per cent of the time ranges from 8 to about 12.5 metres per second, the higher figures being in Scotland.

Positive pressure Infiltration Negative pressure

Positive pressure Infiltration Negative pressure

Negative Wind Pressure

Figure 8.12

Wind pressure and infiltration

Figure 8.12

Wind pressure and infiltration

At the same time, average wind speeds increase by 7 per cent for every 100 m increase in altitude.

Wind speeds can be considerably reduced by the introduction of natural or artificial dampeners. A solid wind break can greatly reduce wind speed in its immediate vicinity but beyond that zone will cause turbulence. On the other hand, an openwork fence with only 50 per cent solid resistance to wind will moderate wind speed over a much greater area. At the same time a timber fence of this nature will be less likely to become a casualty of gale force winds.

Natural features can be effective wind breaks. Even low level planting creates drag, thereby slowing the wind force. Trees are the best option, remembering that deciduous trees are much less effective in winter. As a rule of thumb, the distance from a house to a tree break should be 4-5 times the height of the trees to optimise the dampening effect.

Climatologists predict that global warming will result in wetter winters and much drier summers with droughts a regular occurrence. This gives shrubs and trees a further benefit in the degree to which they protect from the drying or desiccating effect of wind. According to the TV gardening personality Monty Don 'In the British climate, wind is far more of a problem than sunshine and can be drought-inducing in the middle of winter when there is not a ray of sunshine to be seen for days' (Observer Magazine, 19 January 2003).

Wind plus driving rain can affect the thermal efficiency of a property. When brickwork becomes saturated the thermal conductivity of brickwork or blockwork increases since moist masonry transmits heat more effectively than in a dry condition. This problem would be cured with a polymer-based render.

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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