People frequently cite a number of benefits related to underfloor air distribution (UFAD) systems—more flexibility, better indoor air quality, comfort, energy efficiency, and reduced lifecycle costs. These benefits may be realized in practice, however much depends on the system design, building use, climate, and other factors. The focus of this paper is to describe each of these benefits briefly, discuss what is required to take advantage of these potential benefits, and note what is commonly observed in current practice.

High-performance green buildings are often promoted as offering higher quality, more productive environments for their occupants. Yet measuring how successful a building is at achieving this objective can be difficult. Post-occupancy studies are done infrequently and tend to be highly customized for specific applications. The Center for the Built Environment (CBE) at the University of California, Berkeley has developed a web-based occupant indoor environmental quality (IEQ) survey to inexpensively measure occupants’ perception of the quality of their workplace environment. A set of core questions is used to assess occupant satisfaction and comfort with respect to many issues related to green building objectives including indoor air quality, thermal comfort, lighting and acoustics. Custom modules can be added to address issues not covered in the core questions, and the survey can be offered in multiple languages. Surveys assessing other aspects of building quality are also in use, including an operations and maintenance staff survey, and a design and construction process survey. Together this set of surveys provides a complete picture of the quality of the building process, from the planning phase through the occupancy phase. The CBE building quality surveys have been conducted in 45 buildings to date (including three LEED-rated buildings), including office buildings, laboratories, banks and courthouses in North America and Europe. The database of survey responses is growing rapidly and is increasing its utility for benchmarking performance.

Building occupants are a rich source of information about indoor environmental quality and its effect on comfort and productivity. The Center for the Built Environment has developed a Web-based survey and accompanying online reporting tools to quickly and inexpensively gather, process and present this information. The core questions assess occupant satisfaction with the following IEQ areas: office layout, office furnishings, thermal comfort, indoor air quality, lighting, acoustics, and building cleanliness and maintenance. The survey can be used to assess the performance of a building, identify areas needing improvement, and provide useful feedback to designers and operators about specific aspects of building design features and operating strategies. The survey has been extensively tested and refined and has been conducted in more than 70 buildings, creating a rapidly growing database of standardized survey data that is used for benchmarking. We present three case studies that demonstrate different applications of the survey: a pre/post analysis of occupants moving to a new building, a survey used in conjunction with physical measurements to determine how environmental factors affect occupants’ perceived comfort and productivity levels, and a benchmarking example of using the survey to establish how new buildings are meeting a client’s design objectives.

This paper summarizes the results of a large indoor environmental quality survey in office buildings, comparing green with non-green buildings. On average, occupants in green buildings were more satisfied with thermal comfort and air quality in their workspace. However, the average satisfaction scores in green buildings for lighting and acoustic quality were comparable to the non-green average. Comparing complaint profiles of those dissatisfied with lighting and acoustic quality, a higher percentage of occupants were dissatisfied with light levels and sound privacy in green buildings. Our results suggest a need for improvements in controllability of lighting, and innovative strategies to accommodate sound privacy needs in open plan or cubicle office layouts in both comparison groups.

The surface temperatures of radiant floor and ceiling systems should depend on the ambient air temperature, yet the surface temperature limits specified by current standards do not vary with air temperature. In addition, the limits for ceiling temperature are specified in terms of radiant temperature asymmetry, which is difficult to convert into surface temperatures. This paper provides graphs that allow designers to directly determine, for a representative room geometry, the acceptable range of floor- and ceiling surface temperatures as a function of air temperatures.

The graphs were generated using the Berkeley Thermal Comfort Model (BCM). Acceptable and optimal floor or ceiling temperatures were found for a range of air temperatures for normal office work activity level (1.2 met). Acceptability was defined as the absence of whole-body discomfort. Depending on the air temperature, the acceptable floor temperature range is 15-40ºC, wider than that specified in ASHRAE Standard 55 and ISO 7730 (19-29°C). The upper limit of 40ºC is based on avoiding discomfort through skin contact, supported by several studies showing that people are comfortable with floor temperatures near 40ºC. The 15ºC lower limit was chosen to avoid local foot discomfort as reported in a laboratory study. The acceptable ceiling temperature range is 10-50ºC, also wider than in Standard 55 and ISO 7730 (radiant asymmetry <5ºC for a warm ceiling, and <14ºC for a cool ceiling). The maximum temperature of 50ºC was chosen as a reasonable water temperature available from heat reclamation, and it was felt that temperatures below 10ºC were unlikely to be used in any climate because of the risk of moisture condensation on surfaces. The model simulation results were compared with published laboratory experiments on radiant floors and ceilings. The results are in generally good agreement, given a number of uncertainties in reproducing the laboratory conditions and matching a variety of different comfort voting scales.