In earlier work (Axley and Emmerich 2002), NIST developed a climate suitability analysis technique to evaluate the potential of a given location for direct ventilative cooling and complimentary nighttime ventilative cooling. The direct ventilative cooling may be provided by either a natural ventilation system or a fan-powered economizer system. The nighttime ventilative cooling is intended to cool the buildings thermal mass to help manage cooling loads during the following day. The climate suitability analysis technique is based on a general single-zone thermal model of a building configured and operated to make optimal use of direct and/or nighttime ventilative cooling. NIST has implemented this climate suitability methodology via a new tool with additional capabilities including consideration of an adaptive thermal comfort model. This paper describes this new tool and presents results from the application of the adaptive thermal comfort model to analyze the suitability of a variety of U.S. climates for natural ventilation cooling. The adaptive thermal comfort option has the potential to substantially improve the applicability of natural ventilation cooling for many U.S. cities. However, this impact is very dependent on the whether a limit is included for the outdoor humidity. If a dewpoint limit is used, the increase is significant for a dry climate such as Phoenix but much smaller for more humid climates such as Kansas City and Miami. While ASHRAE Standard 55 does not impose a limit on humidity when using the adaptive thermal comfort option, the necessity of limiting humidity for other reasons needs to be carefully considered.
Citation: Energy and Buildings
Pub Type: Journals
Natural Ventilation, Green Buildings, Hybrid Ventilation, Design Method, Climate Suitability, Sustainable Building, Thermal Comfort, HVAC Systems