ASHRAE members have free access to research project final reports. Non-ASHRAE members can purchase research reports for $30 per article from the ASHRAE Bookstore found at this link.
1515-RP: THERMAL AND AIR QUALITY ACCEPTABILITY IN BUILDINGS THAT REDUCE ENERGY BY REDUCING MINIMUM AIRFLOW FROM OVERHEAD DIFFUSERS
TC 2.1, Physiology and Human Environment
Simulations show that reducing zone minimums in a typical office building from 30% to 20% can save $100/k ft2-yr in fan, cooling, and reheat energy (approximately a 10% reduction in total energy use). Multiplied across the millions of square feet of commercial space served by VAV boxes, the potential economic and environmental benefits are substantial. Savings can be achieved in new construction and in existing buildings through low cost control system re-programming. The opportunity for savings in existing buildings with minimal financial investments is a particularly exciting application for this work.
Because this study will involve observations across a range of supply air volumes and temperatures, the study will have an additional benefit of providing ASHRAE with detailed information about local thermal discomfort in actual occupied buildings. This can be used to validate some of the local discomfort provisions in Standard 55, which are at present based solely on laboratory studies.
The research could also have far reaching implications in terms of getting changes made to the ASHRAE Handbook, to manufacturers' literature and to the way engineers calculate minimum flow rates. It will also support proposed changes in Standards 90.1, 62.1 and 55.
843-RP: Human Response to Air Movement-Evaluation of ASHRAE's Draft Criteria
Jørn Toftum, Arsen Melikov, Agnieszka Tynel, Marcin Bruzda, P. Ole Fanger
The aim of this study was to evaluate the present ASHRAE Standard 55-1992 draft criteria and to describe how air movement is perceived at thermal sensations slightly cooler and slightly warmer than neutral. At temperatures 18°C, 20°C, 23°C, 26°C, and 28°C (64.4°F, 68°F, 73.4°F, 78.8°F, and 82.4°F), 40 subjects at slightly cool, neutral, and slightly warm overall thermal sensation were exposed to air velocities that were increased step-by-step from less than 0.1 m/s to 0.8 m/s (19.7 fpm to 157.5 fpm). Subjects who felt cool or slightly cool perceived air movement as being uncomfortable at lower air velocities than did subjects feeling neutral or warmer. No difference in draft sensitivity between subjects feeling neutral, slightly warm, or warm was observed. A smaller percentage of subjects were dissatisfied due to draft than prescribed by ASHRAE Standard 55 guidelines on air movement. The discrepancy could be explained by the effect of thermal sensation and activity level on draft sensitivity. Permissible mean air velocities as recommended by the standard thus provide a conservative upper limit for air velocity that protects occupants who are sensitive to air movement, occupants who feel cooler than neutral, or occupants who are occupied mostly with sedentary work. To accommodate all occupants in a given indoor environment, therefore, it is recommended that air movement generated by the HVAC system be designed according to the criteria in the current Standard 55 to minimize complaints of draft. To provide comfort for occupants who prefer more air movement, local air movement under individual control is easy to generate, e.g., by a desk fan.
1128-RP: Combined Effects of Noise and Temperature on Human Comfort and Performance
Dale K. Tiller, D.Phil., Lily M. Wang, Amy Musser, Richard Moscoso Bullon, Matthew J. Radik, Nicholas Decker, Sandro Plamp
This document describes results from an experiment designed to investigate the combined effects of noise and temperature on human comfort and performance. Research has established that poor lighting, noisy work areas, and/or excessively warm or cold temperatures, can and will compromise occupant performance and satisfaction compared to more comfortable condition. In contrast, strong and reliable links between better indoor environment conditions and increased productivity have remained elusive.
The independent variables manipulated in this experiment included five thermal conditions, two sound qualities, and three sound levels. The effects of the independent variables on the opinions and performance of the subjects used in the experiment were measured using self-administered computer-based tools
1129-RP: Thermal Comfort Models and “Call Out” (Complaint) Frequencies
C. Federspiel
Previous research describes a model that can be used to assign economic cost to thermal discomfort. This is a subject of unquestionable importance to ASHRAE. More research is needed to establish the accuracy of this model so that it may gain acceptance as an economic analysis tool.
The results of this research will impact ASHRAE Standard 55 as follows. The model can be used to optimize building temperature to either minimizing total cost (energy plus service call cost) or to minimizing complaint frequency. These two temperatures could be used as a new basis for the upper and lower limits of the comfort zone. Unlike the existing upper and lower limits, these limits would have an economic basis.
The objective of this research project is to evaluate the accuracy of the complaint model recently proposed.
1160-RP: Experimental Determination of the Limiting Criteria for Human Exposure to Low Winter Humidity Indoors
David P. Wyon, Lei Fang, Love Lagercrantz, P. Ole Fanger
The 2005 ASHRAE Handbook—Fundamentals (ASHRAE 2005) states that Liviana et al. (1988) found that eye discomfort increases with time if the dew-point temperature is less than 2C (35.6F). This was the basis for the minimum RH that appeared in the thermal comfort zones that were until recently recommended in ASHRAE Standard 55 (ASHRAE 1992, 1995). They prescribed a lower humidity ratio limit of 4.5 g/kg (31.5 gr/lb), corresponding to 30% RH at 20.5C (68.9F). This lower limit is no longer recommended in the latest version of the same standard (ASHRAE 2004). According to section 5.2.2, “Humidity Limits” (ASHRAE 2004), “There are no established lower humidity limits for thermal comfort; consequently, this standard does not specify a minimum humidity level. However, non-thermal comfort factors such as skin drying, irritation of mucus membranes, may place limits on the acceptability of very low humidity environments.” ANSI/ASHRAE Standard 62-1989 (ASHRAE 1989) recommended an optimum indoor humidity range of 30% to 60% RH, while later revisions (Standards 62.1 and 62.2) no longer recommend a lower humidity limit. The low relative humidity limits originally prescribed in both of these ASHRAE standards may have been intended to minimize dry skin, eye irritation, respiratory infections, allergy and asthma, viability and virulence of bacteria and viruses, ozone production, etc.
1161-RP: Operable Windows, Personal Control, and Occupant Comfort
Gail S. Brager. Gwelen Paliaga, Richard de Dear
Past research (ASHRAE RP-884) demonstrated that occupants of naturally ventilated buildings are comfortable in a wider range of temperatures than occupants of buildings with centrally controlled HVAC systems. However, the exact influence of personal control in explaining these differences could only be hypothesized because of the limits of the existing field study data that formed the basis of that research. The objective of ASHRAE RP-1161 was to quantitatively investigate how personal control of operable windows in office settings influences local thermal conditions and occupant comfort. We conducted a field study in a naturally ventilated building where occupants had varying degrees of control over the windows. Utilizing continuous measurement of each subject’s workstation microclimate, plus a Web-based survey that subjects took several times a day and was cross-linked to concurrent physical assessments of workstation microclimatic conditions, we collected over 1000 survey responses in each of the two main seasons. The data show that occupants with different degrees of personal control had significantly diverse thermal responses, even when they experienced the same thermal environments and clothing and activity levels. Our findings offer further empirical support for the role of shifting expectations in the adaptive model of thermal comfort.
1332-RP: Revisions to the ASHRAE Thermal Comfort Tool to Maintain Consistency with Standard 55-2000
Charlie Huizenga
In 1997 ASHRAE published the ASHRAE Thermal Comfort Tool to provide a simplified, consistent method for evaluating thermal comfort under a range of thermal conditions. The software is consistent with ASHRAE Standard 55-1992 and indicates whether a set of environmental conditions is in compliance with that standard. ASHRAE subsequently published ASHRAE Standard 55-2004, which incorporates several important changes from Standard 55-1992. The purpose of this project was to make several important changes to the existing ASHRAE software so that it is consistent with the new standard. The most fundamental changes to the software were to change the basis for compliance with Standard 55-2004 to PMV rather than ET and to include the adaptive model, however many changes were made to the software to make it consistent with 55-2004 and to improve the user interface.
