S u s t a i n a b l e H o u s e
Dec 24, 2015
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Passive Solar Design.
Passive solar design is the process of designing
and orientating new buildings or modifying existing
ones to purposefully capture the suns natural energy.
The Romans first discovered that by glazing the
south-facing windows and porches of their buildings,
solar energy could be trapped, heating the building and
keeping the temperature constant into the night. This
simple phenomenon is called the "greenhouse effect",
today we call a building that uses the greenhouse effect
a "passive solar building".
The basic principles of passive solar design are;
• Orientating buildings to have much larger south-facing windows (more sunlight exposure) than at the north side.
• Interior spaces requiring the most heating and lighting should be along the south facing side, with less used rooms (utility room, garage etc.) on the north side.
Active Solar Design.
Active Solar Heating systems are most commonly
used to supply domestic hot water for washing and
heating. A collector array (absorber) is mounted on
the roof which soaks-up the sun's radiation and
increases in temperature, this heats a fluid
circulated between the absorber and the water
tank, thus heating the water. Enhanced performance
systems exist using evacuated glass tubes, which
minimise heat losses. These can produce hot water
on a cold (sunny) winters day even when
temperatures are well below freezing.
The UK sits on a northern latitude, which means we receive roughly half the amount of solar energy as some of the sunnier climbs of the world. Theoretically this is still enough to provide all of our water and space heating but in reality seasonal undulations make year-round solar water heating, at present, unrealistic. Installation costs are also currently too high for most (£2000 - £6000). But as the technology becomes more widespread and new buildings are designed to incorporate active solar heating systems as standard, so prices should fall.
Photovoltaic (PV) cells.
A solar photovoltaic (PV) cell is an electronic
device that produces electricity when light
falls on it. As the light is absorbed by the PV
cell it frees up electrons present in the cell,
as the electrons move from the cell, they
carry with them an electrical charge and are
sent to a load such as a calculator or to
storage, such as a battery.
A single PV cell can only absorb a small amount of light at a time. So several cells are usually interconnected to form modules to provide larger amounts of electricity. Groups of modules can be mounted together to form a panel. Panels can be interconnected to form a photovoltaic array; these can vary in electrical power depending upon size, from a few watts to thousands. These systems can last a long time; the expected life span is at least 25 years.
PV panels and arrays are becoming increasingly popular and being deployed around the world. Their potential as stand-alone systems is recognised particularly in areas where grid-connected electricity is not available. PV panels are also being integrated into existing buildings by replacing the traditional materials of the roofs and facades. Buildings with PV panels which generating more electricity than they use can sell back the surplus power to the national grid.
Turf and Green Roofs.
The environmental benefits of turf and green
roofs are widely recognised, while roof gardens
and roof terraces provide much-needed outdoor
space in urban areas.
Due to the high degree of insulation that they
provide, green roofs are known for their ability to
provide an extremely constant temperature
throughout the year. During the winter they keep
the heat in, and in the summer they provide a
relatively cool environment. Green roofs also have
the ability to soften harsh edges of buildings in
sensitive environments, making them blend in with
the surrounding area.
Turf and green roofs provide habitat for insects and
other wildlife. Where new buildings are built on
greenfield sites, this new habitat can replace the
habitat that would otherwise have been lost
Greywater Recycling.
"Greywater recycling" is typically defined as
being water from the bath, shower, wash hand
basin. The ideal situation for ‘Greywater’ is in
living accommodation where sufficient amounts
are generated daily for reuse in toilets, washing
machine and outside tap.
Rainwater Harvesting.
"Rainwater harvesting" is typically defined as
being water collected from roofs via traditional
guttering, through down pipes to an
underground tank(s). Delivered on demand by
an in-tank submersible pump direct to toilets,
washing machine and outside tap use. More than
50% of mains water can be substituted by rainwater.
Energy Efficient Materials.
InsulationHigh performance, non polluting.
“Zero Ozone Depletion Potential
(ODP) non-fibrous insulation has
emerged from this major study as
being amongst the most
environmentally sustainable forms
of insulation.”
Glass ( windows )Windows have long been used in buildings for
day lighting and ventilation. Many studies have
even shown that health, comfort, and productivity
are improved due to well-ventilated indoor
environments and access to natural light. However,
windows also represent a major source of unwanted
heat loss, discomfort, and condensation problems.