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 1 of an eight-part series.

The primary objective of the guide is to help architects, engineers and designers construct buildings in hot climates that are as close to net-zero as possible.

The primary objective of the guide is to help architects, engineers and designers construct buildings in hot climates that are as close to net-zero as possible. Victor He/Unsplash

As the global climate continues to warm, the need for sustainable, low-carbon, and low-energy solutions in building design has never been more urgent, especially in hot climates.

The ASHRAE UK chapter is developing the Hot Climate Design Guide, a resource that aims to address the unique challenges of designing buildings in hot, dry and temperate climates, with a strong focus on passive and hybrid cooling solutions. Scheduled for publication by 2026, this guide will provide detailed, practical design methods and energy-efficient solutions for new buildings in regions that experience long, hot summers.

The primary objective of the guide is to help architects, engineers and designers construct buildings in hot climates that are as close to net-zero as possible. Achieving net-zero buildings in hot climates is not only critical for reducing energy consumption but also essential in mitigating the environmental impact of building operations. The guide will explore the integration of passive solar design with mechanical cooling systems, highlighting how a hybrid approach can provide the most energy-efficient and cost-effective solutions.

Unlike traditional buildings, which are typically designed with air conditioning as the primary means of cooling, the guide will encourage the use of passive cooling strategies wherever feasible, supplemented by mechanical systems only when necessary. This approach, referred to as hybrid solutions, aims to reduce energy consumption and operating costs. By combining passive techniques like natural ventilation and shading with mechanical systems such as chillers and heat pumps, the guide advocates for a more sustainable and cost-efficient building design.

Key concepts and strategies

  • Passive solar design and hybrid systems: Passive solar design harnesses natural energy sources, such as sunlight and wind, to maintain indoor comfort. In hot climates, this may include using solar shading, strategic window placement and high thermal mass materials to reduce heat gain. However, in extreme conditions, passive solutions alone may not suffice, which is why the guide also emphasises hybrid solutions, integrating mechanical systems to supplement passive strategies when necessary.
  • Thermal storage for efficient cooling: Thermal storage systems, which store cool air or water at night, can be used to provide cooling during the hot daytime hours. Many hot climates, such as those in Africa and the Middle East, experience significant temperature differences between day and night, creating an opportunity to use nighttime cooling for daytime relief. This approach could involve the use of materials with high thermal mass or running chillers and heat pumps at night when energy consumption is lower and more efficient.
  • District cooling: The guide will explore the benefits of district cooling systems, which centralise cooling generation and distribute it across multiple buildings. These systems are particularly effective in hot climates, where individual air-conditioning units would require substantial energy. District cooling reduces energy consumption and provides a more sustainable, cost-effective solution than traditional air-cooled chillers.
  • Daylighting and natural ventilation: Maximising natural light and promoting ventilation are vital components of building design in hot climates. Not only do they reduce the need for artificial lighting, but they also contribute to better air quality and occupant comfort. The guide will provide strategies for optimising daylighting and designing for natural ventilation, reducing reliance on artificial cooling systems.
  • Outdoor comfort in hot climates: While much of the focus in hot climate design is on indoor comfort, it is also essential to consider the outdoor environment. Designing shaded outdoor spaces and cooling the exterior of buildings can create comfortable environments for people to gather and socialise even in extreme heat. The guide will provide strategies for achieving such outdoor comfort, emphasising low-cost, energy-efficient solutions.

Continued in Part 2…