Status (updated 11/5/2007): Ongoing
Funding sources: CBE Industry Consortium
Project Objective
Characterize the opportunities and limitations of radiant cooling strategies for North America, and contribute to improved understanding of design tools, methods, and applications. This work is planned as a multi-project research area.
Significance to Industry
Radiant cooling has gained recent popularity in Europe and Canada because it offers the potential to reduce cooling energy consumption and to reduce peak cooling loads when coupled with building thermal mass. Radiant cooling refers to any system where surrounding surface temperatures are lowered as means of removing sensible heat gain and thus contributing to thermal comfort. Some radiant systems circulate cool water in specialized panels; other systems cool the building structure (slab, walls, ceilings, and/or beams). Because radiant surfaces are often cooled only 2-4°C below the desired indoor air temperature, there are many opportunities for innovative cooling sources such as night fluid cooling, ground-coupled hydronic loops, and indirect evaporative cooling.
High performance buildings with lower cooling loads may offer the best opportunities for radiant cooling applications. In addition, the limited cooling capacities of some low-energy cooling strategies such as displacement and natural ventilation can be extended when combined with radiant cooling.
Research Approach
For the first phase of this project we conducted a literature search on modern radiant cooling systems, focusing on design issues, case studies and open research questions. We conducted interviews with industry professionals with expertise with these systems, including CBE partners, experienced designers, building operators, and researchers. We produced a technical paper summarizing our assessment of radiant cooling applications in North America.
For the current phase of this research area we will start with evaluation of existing and emerging design and simulation tools to assess which are most effective and where further development is most needed. For example, we will compare the capability of Energy Plus with that of Integrated Environmental Solutions’ Virtual Environment.
CBE will seek to uncover a deeper level of information regarding where and when radiant cooling is appropriate and the drivers behind its successful application. To this end, we plan to conduct a small number of field studies, benefiting, at least in some cases, from data collection and continuous monitoring undertaken by the owners of noteworthy radiant cooling projects and supplementing that with our own measurements. Parameters investigated will include energy efficiency, thermal performance, and cost. Where possible, we will administer a CBE post-occupancy survey and will attempt also to collect measurements regarding acoustic concerns, particularly in spaces that incorporate exposed radiant slabs. Finally, we will use simulation tools to assess energy, thermal, and energy-related economic performance across a representative range of North American climate zones. This assessment will begin by looking at a baseline ASHRAE-90.1-2004-compliant office building with and without radiant cooling. We will then expand the investigation to integrated radiant cooling applications that include UFAD, DOAS, pre-cooling, low-energy cooling sources (evaporative, night-sky, etc.), low-energy building envelopes, and/or other similar strategies.
Publications and Reports
Weeks, K., D. Lehrer and J. Bean, 2007. A Model Success: The Carnegie Institute for Global Ecology, Center for the Built Environment, University of California, Berkeley, May.
Moore, T., F. Bauman and C. Huizenga, 2006. Radiant Cooling Research Scoping Study. CBE Internal Report, April.
