Paul Cooper

This paper details an experimental and analytical investigation of flow in an enclosure containing a cold plate located on a wall above a hot plate. The colliding boundary layer flow that results and consequent thermal stratification in the enclosure has been modelled first using a water-filled scale model. The full scale situation corresponds to a room with a cold window surface above a heater panel on one wall. A flow element model has been developed using standard boundary layer and plume flow relations to model the component flows in the enclosure. The model provides a good estimate of mean temperature in the enclosure and a conservative prediction of the stratification between the top and bottom.

Air conditioning (A/C) is generally responsible for a significant proportion of total building energy consumption. However, occupants’ air conditioning usage patterns are often unrealistically characterised in building energy performance simulation tools, which leads to a gap between simulated and actual energy use. The objective of this study was to develop a stochastic model for predicting occupant behaviour relating to A/C cooling and heating in residential buildings located in the Subtropical Sydney region of Australia. Multivariate logistic regression was used to estimate the probability of using A/C in living rooms and bedrooms, based on a range of physical environmental (outdoor and indoor) and contextual (season, day of week, and time of day) factors observed in 42 Sydney region houses across a two-year monitoring period. The resulting models can be implemented in building energy performance simulation (BEPS) tools to more accurately predict indoor environmental conditions and energy consumption attributable to A/C operation.

Rental houses in Australia represent approximately one third of all homes, and this proportion has been growing over recent decades. However, the quality, comfort and environmental credentials of these houses are often poor, particularly when compared to owner-occupied homes. With climate change, the urgency increases to move to a more sustainable built environment. Consequently, exploring how to make rental properties more sustainable warrants further investigation and action. Using data gathered from a broad range of experts through a four-stage Policy Delphi technique, findings reveal four key enabling forces: communication, facilitation, incentivization, and regulation. These forces both influence and are influenced by rental market conditions. A conceptual framework is presented which highlights the interplay between the stakeholders and enabling forces, which has the potential to lead to a Win-Win-Win scenario for landlords, tenants and the environment. With a clear social and environmental imperative to move to a more sustainable rental sector, this research presents a pathway to reach this goal.

Plumes generated by vertically distributed sources of buoyancy have been observed to have substantially lower entrainment coefficients than their equivalent-geometry constant buoyancy flux plumes. Two differences between distributed and localized sources of buoyancy are the presence of a wall shear stress at the source and that non-ideal source conditions are distributed over the whole height of the enclosure for a vertically distributed source. Herein the impact of non-ideal source and boundary conditions on vertically distributed plumes is analysed. It is shown that, at small heights, the plume volume flow rate is significantly influenced by the wall-source volume flux. At larger heights the wall-source buoyancy is greater than the mean plume buoyancy, creating a non-self-similar horizontal buoyancy distribution within the plume. Recent experiments into the behaviour of a vertically distributed source of buoyancy in a confined region have also shown that the plume partially detrains in the stratified region of the enclosure. This detrainment has not been observed for constant buoyancy flux plumes in a confined region. Although models have been proposed to quantify the detrainment process, it is still unclear why vertically distributed buoyancy sources detrain while constant buoyancy flux plumes do not in the same physical geometry. The impact of source and boundary effects on previously published experiments on vertically distributed plumes are reviewed and the possible implications for plume entrainment and detrainment are discussed.