Looking at optimal temperature control in buildings.

 

According to the Cape Town 2011 State of Energy and Energy Futures Report, industry, including the building sector, accounts for 43% of the South African annual energy consumption.

The heating and cooling of buildings contribute significantly to the demand placed on the grid. According to the International Journal of Thermal Sciences (2003), time-of-use electricity rates encourage the shifting of electrical loads to off-peak periods at night and weekends. Therefore the goal of temperature control in buildings is to ensure minimal energy consumption while still maintaining optimal comfort levels.

Temperature control in irregularly occupied buildings has traditionally made use of basic control methods, which are usually not able to solve all the challenges encountered. Recently, however, there has been increasing interest in the concept of modern control strategies for integrated building systems.

 

Did you know?

The thermal capacity of a typical concrete building structure is approximately 2-4 Wh/°c on 0,09m² floor area.

 

All materials and layers in a building assembly have a level of resistance to heat flow. Materials with lower K-values are often used in building assemblies, as they are able to retard the flow of heat.

In the Thermal Insulation Association of South Africa’s (TIASA) insulation handbook, emphasis is placed on the retardant qualities of insulation materials. According to the handbook, no matter how much insulation is applied, the reverse flow of heat to ambient can never be stopped.

The primary reasons for insulation are to:
• Conserve energy.
• Reduce heat loss or gain.
• Maintain a temperature condition.
• Maintain the effective operation of equipment or chemical reaction.
• Assist in maintaining a product at a constant temperature.
• Prevent condensation.
• Create comfortable environmental conditions.
• Protect personnel.

When trying to establish the most efficient insulation system, the handbook also notes that there are various factors that have an influence on the final design of the insulation system. These factors include the location, temperature and atmospheric conditions and other special or service conditions.

 

The design of an insulation system is governed by the following insulated operating values:

• Emissiveness.
• Thermal conditions – Heat loss/heat gain.
• Process temperature drop or rise.
• Condensation prevention.
• Personnel protection temperature.
• Optimal economic conditions.
• Thermal conductivity of insulation material.
• Ambient temperature.
• Wind velocity.

 
Full thanks and acknowledgement are given to  TIASA, www.bwk.tue.nl and the Cape Town 2011 State of Energy and Energy Futures Report for the information given to write this article.