By Eamonn Ryan
The following article is derived from an ASHRAE UK presentation on ASHRAE UK chapter’s upcoming Hot Climate Design Guide, by Frank Mills, FASHRAE and professional consulting engineer. This is Part 7 of an eight-part series.
Covered car parks or multi-story parking structures, located farther from the building, can reduce the amount of heat transferred into the building’s interior. Freepik.com
The guide explores how the surrounding landscape plays an important role in how a building performs in hot climates. A typical issue is the creation of urban heat islands, where hard surfaces like asphalt, concrete and metal absorb and radiate heat, significantly increasing local temperatures. Car parks, particularly those with extensive paved areas, are a major contributor to this phenomenon, as car surfaces can reach temperatures above 60°C in the summer heat.
In the case of a building surrounded by such hard-standing surfaces, the temperature of the surrounding environment can raise the internal temperatures of the building as well, even if windows and doors are closed. This means that buildings must be designed with a buffer zone between them and sources of intense heat like car parks. Covered car parks or multi-story parking structures, located farther from the building, can reduce the amount of heat transferred into the building’s interior.
Designers need to address these issues by planning landscapes that incorporate green spaces, shade trees, and other cooling features. In addition to reducing heat gain, these features can also enhance the aesthetic and functional value of the space, contributing to the well-being of building occupants.
Understanding humidity and temperature
The Mahoney Tables offer crucial insight into the interactions between temperature, humidity, and building performance. By dividing the climate into different categories—humid, arid and semi-arid climates—the tables provide designers with a structured way of approaching building design based on specific climate characteristics. These tables also detail the relationship between the mean temperatures, seasonal variations and relative humidity levels at different times of day and night.
For instance, when designing for an arid climate, where humidity is low and daytime temperatures can reach over 50°C, buildings need to prioritise strategies for heat mitigation and efficient cooling. Conversely, in humid climates, the focus might shift toward improving ventilation and reducing moisture buildup inside the building.
The Mahoney Tables are designed to guide engineers through these complex climatic factors by offering practical design indicators. These include recommendations for building layout (such as building orientation), wall and roof characteristics, window openings and the inclusion of outdoor sleeping areas, which are common in hot climates where nighttime temperatures drop sufficiently for comfortable outdoor living.
