Economic growth and expanding populations in hot and humid climates are contributing to a rapid and concerning increase in the use of air conditioning in buildings around the world. This is boosted by several related factors, including urbanization, climate change and higher expectations for comfort as incomes grow in developing countries. Because this increase in air conditioning appears almost inevitable, it is now critical to guide this demand towards sustainable solutions to mitigate significant potential climate change impacts.

CBE is part of a team working to address these challenges, in collaboration with Lawrence Berkeley National Laboratory. The new research program, “Resilient Cooling for Buildings,” is organized under a program launched in 2019 and supported by an international association of governments, industry and researchers, and with support from the U.S. Department of Energy’s Building Technologies Office.

The overarching goal of Annex 80 is to support the rapid adoption of resilient, low-energy and low-carbon cooling systems for buildings. This work will also serve to help cities and communities better contend with climate-based and demand-based power outages. Earlier IEA annexes (research programs) dealt with aspects of low-energy and low-carbon cooling with a focus on specific technologies. A goal of Annex 80 is to build on these earlier results, integrating the previous findings into a wider holistic approach. The international team will examine ways to reduce external heat gains, explore personal comfort apart from cooling spaces, and new ways to remove sensible and latent heat (humidity) from indoor environments. The extensive list of topics includes advanced cool envelope materials, innovative windows and shading, high-performance HVAC systems, ventilated facades, the use of natural heat sinks, and other topics as described in the Annex 80 overview.

CBE researchers, led by Ed Arens and Hui Zhang, will supply expertise in air movement and physiology during this project. The first phase, currently underway, is investigating three energy efficient strategies to providing comfort in warm environments, and establishing key performance indices for them:

  1. Occupant cooling by fans — the convective cooling of occupants by air movement provided by room or ceiling fans in the space.
  2. Personal comfort systems — devices that are directly controlled by individual occupants to heat and/or cool the occupants or their immediate thermal environments. This includes wearable devices.
  3. Occupant cooling by natural ventilation air movement — the convective cooling of occupants by indoor air motion (rather than temperature reduction) provided by windows and other openings in the building envelope.

The CBE researchers will quantify the effect of these strategies, investigating the amount of time that indoor temperatures will be outside standard comfort zones (exceedance hours) under various conditions of curtailed electricity. This will be done for three sets of buildings: (1) naturally ventilated (NV) buildings with no air conditioning; (2) mixed-mode buildings that combine NV and air-conditioning; (3) and fully air-conditioned buildings.

CBE will also identify barriers to implementing resilient cooling strategies, provide solutions to overcome the barriers, and provide design and operation recommendations. Part of this work will be done in collaboration with the committees for ASHRAE Standard 55 (Thermal Environmental Conditions for Human Occupancy) and Standard 216P (Methods of Test for Determining Application Data of Overhead Circulator Fans). One expected result will be to develop design guidance for zero-energy and very-low-energy cooling strategies.

The project in support of Annex 80 started in fall 2019, and is expected to last four years. We look forward to sharing results as the project progresses, and sharing new resources to advance the next generation of sustainable, low-carbon buildings in the coming years.

Share This