Division of Information Technology, Engineering and the Environment
Sustainable Energy Centre
Sustainable Energy Centre
Area: Mechanical Engineering
Potential research area: Sustainable
thermal energy
Insulation is a
critical component to energy efficient building design. Current building
regulations only consider two dimensional conduction through timber and
steel frames which act as thermal bridges across the insulation path.
Accounting for three dimensional conduction at edges, corners, doors and
windows can reduce the insulating performance of a wall or roof by 30%.
An experimental investigation is required to determine the 3D thermal
resistances of walls and roofs, and determine energy efficient solutions
to minimising these effects. The study will also involve 3D
conduction modelling using CFD.
Area: Mechanical Engineering
Potential research area: Sustainable
thermal energy
Sensible water
cooling systems are capable of delivering significant amounts of cooling
in temperate climates for commercial buildings. Producing low
temperature water using cooling towers can use 10 times less energy than
conventional chiller systems. However these systems are
ineffective during the daytime. The application of storage will
enable cooling towers to operate at night storing cooling capable of
providing adequate cooling during the day. Phase change materials
offer a significant capacity in storing cooling energy. With high
levels of storage this system may be capable of eliminating the need for
conventional chillers in temperate climates.
Area: Mechanical Engineering
Potential
research area: Thermal comfort and energy
Thermal comfort within indoor environment can be achieved through
a convective system, a radiant system or a combination of both. Various
systems which utilise these concepts have been developed. The concept of
operative temperature was introduced to better represent human sensation
of the combined effect of the following thermal comfort parameters: air
temperature, mean radiant temperature, relative humidity, air velocity,
metabolic rate and clothing insulation value (Fanger, 1972; ASHRAE
(2005)). For conditions
normally encountered in built environments, ASHRAE (2005) has defined a
comfort envelope for winter and summer. According to this, the winter
acceptable operative temperature range starts from 20.3ºC at 18ºC WB to
around 24.5ºC at about 25% relative humidity (RH). At 50% RH the winter
comfort temperature range is 20.4ºC – 23.6ºC. During the last decade,
research has led to a simple expression of the (comfort) operative
temperature as a function of outside temperature only. For example, for
Pakistan climatic conditions, Nicol et al. (1999) found that
comfort temperature, TC, can be expressed as TC =
18.5 + 0.36 * Tmo, where Tmo is the monthly mean
of the outdoor air temperature. Numerical work by Halawa et al. (1993)
indicated that integration of operative temperature sensor (and an
operative temperature thermostat) in an air conditioned zone is
possible. However, such a concept may not be practical in a situation
where mean radiant temperature effect from building surfaces is not
significant. For convective cooling and heating, the introduction of
operative temperature as the controlled variable may slightly increase
the cooling or heating load. For radiant floor heating, on the other
hand, the effect of mean radiant temperature is significant. The surface
of the temperature heated by an “active element” embedded in the floor,
ceiling or a wall can be significantly higher than that of room air
temperature. This will affect the thermal comfort condition and the
heating requirement of the room.
The proposed research project will evaluate and compare the
thermal performance and thermal comfort conditions created by
convective and radiative heating
systems serving the same indoor conditions.
