Assessing Indoor Environmental Quality in a Crowded Low-Quality Built Environment: A Case Study

Abstract

Home heating, cooling and ventilation are a major concern for those living in low-quality built environments, particularly those with high occupancy rates (crowded houses). In New Zealand, both owner-occupiers and tenants can experience problems associated with poor Indoor Environmental Quality (IEQ), such as poor thermal comfort and dampness, when Heating Ventilation and Air-Conditioning (HVAC) systems are not installed, improperly installed or too expensive to run. Occupants of poorer households are the most affected by high installation or running costs of HVAC systems, and are also more likely to live in households with a higher level of crowding. Poor IEQ in housing is associated with adverse health outcomes, particularly respiratory illness. This paper outlines the IEQ problems experienced by households living in an area of New Zealand with higher levels deprivation and shows how an HVAC system could be employed to remedy poor IEQ. This report presents a case study of a house with poor IEQ that was selected from a survey conducted across 24 homes in the Manukau, Auckland region of New Zealand. The IEQ results are presented for this house, which performs poorly in terms of relative humidity, temperature and thermal comfort. This house is then analysed using the computational fluid dynamics (CFD) approach in ANSYS CFX 2021R1 based on the American Society of Heating, Refrigeration and Airconditioning Engineers (ASHRAE) standard 55-2017 and a model of temperature and air flow is created in the software, which can identify ways to improve these parameters in the house. These results are compared with the New Zealand Healthy Homes Standards 2019. The simulation showed the system was capable of lifting the indoor temperature to above 21 ℃, eliminating cold spots and improving thermal comfort, and reduced relative humidity to below 50%.