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Latest News
AccuRATE V1.1.3.0
The latest version of 2nd Gen BTP
Assessment tools has been released.
DoP agree to a new Pilot to
commence early February 2007.
BASIX (DIY)
Review
ABSA instrumental in securing DoP
DIY Sustainability Tool - DoP Review...not independent but a starting point
Visit the ABSA Site for further
details.
DIY found to lower the standard of
Residential Building BTP in NSW - varies between 200% to 400% below Simulation
Method when compared with NatHERS and far more variation expected to AccuRATE.
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 Natural
Cooling
Building
Cooling Systems
In an arid area, cooling of
buildings for comfort is a high priority.
Conventional solutions assume a building developed to average
standards, with mechanical systems added to change air temperatures back to the
comfort range.
Such systems include reverse cycle air conditioners, geo-thermal
systems, and evaporative cooling.
The first two systems use electricity in
their action to absorb heat from the air and pump it away. In the case of the
air conditioner, the heat ejection is often into air substantially warmer than
the interior space. As well, the compressor may be in direct sun or situated in an area of
trapped warm air as a consequence the system struggles to meet and maintain load
demands.
All these
systems utilise electricity at a rate higher than electricity use with the generation capability
of small renewable energy systems.
Evaporative systems generate cooling by
increasing the latent heat capacity of the indoor air by adding moisture an
acceptable strategy in dry warm climate areas.
This practice focuses on reducing dependence
on any
mechanical system to achieve comfort in buildings.
This is achieved by incorporating
appropriate orientation, wall openings, thermal mass and insulation within the building,
and designing a building layout to the climate responsive ESD principles described
in this site.
Where continuous periods of hot weather are prevalent,
ESD principles can
usefully be enhanced with environmental systems which to some degree replicate
cooling of conventional systems.
The Cooling tower is such a system.
- The principle is to humidify the air volume at the top of a shaft. The
increased mass of that air is at higher temperature than ambient descending into the building through its own
mass drawing after it new air at
the top of the shaft which in turn is humidified.
- Early examples of such evaporative air conditioning
were used centuries ago
in the Middle East, with porous ceramic pots leaking moisture into the air at
the top of a shaft or ceiling space.
- Today the benefits of such a system include the low water and energy
requirements; about 30% and 15% respectively compared to comparable
evaporative air conditioners. The cooling tower avoids all energy use except
the pump to supply the tower head drip system.
- Testing of such systems commenced in Arizona in the late 1980's, and
modelling was published by Prof. Baruch Givoni of UCLA in 1995.
The first proposal was by Paul F. Downton for
towers as part of the Halifax EcoCity Project in 1992.
These towers
(7 in total at 1000m3 volume each servicing the 300 apartment project) were
modelled on the UCLA basis as validation in 1995.
Cooling tower action is dependant on concurrent air
flow from the
building. In the US examples, a separate thermal chimney was built-in in local
examples in South Australia the venting action of the thermal temperature imbalance across the
sunny-side/shade-side of the building itself are used.
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