Approaches to energy conservation in existing buildings : with reference to NZ tertiary libraries

Abstract

The problem of over-consumption of natural resources and the consequence of environmental damage may drive people to change their attitude to using the resources, including a change to their behaviour in using energy. As the building sector uses 30% - 50% of the total energy in many countries, it may be an important issue that concerns people's behaviour. In New Zealand, although many investigations for building energy conservation have been conducted, energy consumption in some buildings is still wasteful. In some types of buildings, such as tertiary institutes, especially their libraries, energy consumption profile and conservation potential have not been revealed. To achieve energy savings in a building, an analysis of the energy performance is an important step. However to obtain building energy performance data, a purely theoretical solution is always difficult or impossible and experimental determination is not affordable. Computer simulation programs, such as DOE-2 have reduced the difficulties of tracing energy performance in buildings. This research gives an example of use of this simulation tool to build a prototype energy performance model for an existing building. Through generalisation of the built model, analysing energy performance in this type of building can be undertaken. Building energy conservation includes preventing wasteful use of energy and increasing energy efficiency. In any building energy performance system, energy efficiency may be defined as a ratio of output energy to the total required input. In an existing building, the desired output energy is comprised of two parts: one part is wasted energy through inadequate design, management or usage and another part is the "net useful energy" (NUE). In the NUE, part is consumed by the system or equipment to overcome energy transfer resistance, the remaining part is the "Effective Energy" being consumed in a required form. This part of energy still can be wasted, for instance, if the indoor thermal condition is not set at a reasonable level. The details of each part of the system are complicated. In this thesis the main discussion is for preventing waste of energy while keeping indoor thermal conditions at a reasonable level.