Tidal Current Energy

Smart Energy Houses of the Future
the building can protect windows that would otherwise be exposed to direct
summer sun. Balcony overhangs and inset windows are clear examples.
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1.1.3 . Solar energy
The goal of passive solar heating systems is to capture the sun’s heat within the
building’s elements and release that heat during periods when the sun is not
shining. At the same time that the building’s elements (or materials) are absorbing
heat for later use, solar heat is available for keeping the space comfortable
(not overheated).
South-facing glass admits solar energy into the house where it strikes directly
and indirectly thermal mass materials in the house, such as masonry floors and
walls. The basic principles can be observed in ancient Greek architecture, where
façades of villas were protected by rows of columns, providing shade in summer
but allowing heat into the building in winter.
Conservatories are an effective means of bringing thermal energy into houses
by means of conduction through a shared mass wall in the rear of the sunroom
or by vents that permit the air between the sunroom and living space to be
exchanged by convection. A south-facing home having an attached conservatory
with solar panels can typically cater for up to 50% of a household’s hot water.
1.1.4 . Compactness
The relationship between the building envelope and the internal space is critical
for energy control. Compact design makes best use of the heat trapped within
the building, and needs to be thought through right from the initial floor plan.
1.1.5 . Airtightness and ventilation
Arab architects used wind scoops and interior courtyards to exploit natural
air movements for cooling. In the early 16th century, Leonardo da Vinci built
the first mechanical fan to provide ventilation: a water-powered device. The
Romans ’ knowledge of the basic physics of air movement allowed them to make
effective use of both natural heating and ventilation, and these principles are to
be seen today in buildings which utilize the buoyancy effect created by stratified
warm air – the thermo-syphon or stack effect. Figure 19.1 shows a demonstration
house with solar lantern utilizing this effect to provide solar gain in winter
at any site orientation; the louvres block summer sun and control natural light.
The requirements of substantial insulation and airtightness present challenges
for ventilation, which becomes a delicate balance between thermal efficiency
and the supply of fresh air, especially where the building is to be naturally ventilated.
With the aid of CFD modelling and readily available electromechanical
devices for operating windows and vents, it is straightforward to design buildings
to use controlled natural ventilation, responding to the exterior climate
through sensors and an optimizing controller. However, although this solution
is finding application in office buildings, the sophisticated control equipment
required is not cost-effective for homes, and furthermore such buildings do not
approach zero-energy operation.