This paper describes the instrumentation and measurement protocol used in ASHRAE research project RP-462, field study of environmental conditions and occupant comfort in 10 office buildings located in the San Francisco Bay region. During this study, we made a total of 2342 visits to 304 participants during two seasons collecting a full set of physical measurements and subjective responses at each visit. In this paper we describe the design of equipment and techniques for gathering physical measurements with the detail and accuracy required by both ASHRAE Standard 55-81 (ASHRAE 1981) and ISO Standard 7726 (ISO 1985). In a addition, the project developed a laptop microcomputer-based thermal assessment survey that collected a substantial subjective data set in machine-readable form. These components performed reliably during nine months of field use, providing a detailed description of the monitored workstation environments with a concurrent portrait of subjective occupant response. The system is recommended for further use.
This paper reports the results of recently completed laboratory and field measurements investigating the thermal performance of an occupant-controlled desktop task conditioning system. The laboratory experiments were performed in a controlled environment chamber configured to resemble a modern office space with modular workstation furniture and partitions. Velocity and temperature distributions were measured throughout the test chamber for a range of test conditions to investigate the effects of supply volume and direction, supply outlet size, and heat load levels (both uniform and nonuniform) in the space. Comfort model predictions are presented to describe the degree of environmental control and range of occupant comfort levels produced in the workstations. Individual desktop units in side-by-side workstations having significantly different heat load levels could be adjusted to maintain close to comfortable conditions, demonstrating localized comfort control.
The field study was performed in a small demonstration office containing two permanent data acquisition systems capable of monitoring in detail the thermal and energy performance of the office, including four installed desktop task conditioning units. Portable measurement methods were also used to assess the thermal comfort of the workers occupying the office. Initial results from the field study demonstrate the occupant response and use patterns of the desktop system, typical energy use pattrns, and the effect of the desktop system on local air velocities and thermal comfort within the workstations.
Field tests were performed in a office to (1) investigate the desktop conditioning system (DTC) performed in situations when demand for the local capabilities may be increased; and (2) compare DTC performance to that of a conventional overhead system under similar high heat load conditions.
When the wall thermostat temperature was maintained at 26°C to 27.5°C, DTC was able to maintain average temperatures in the workstations to be 1 to 2°C lower than the thermostat temperature. Under increased activity levels, DTC could be adjusted to maintain similar comfort conditions, although each subject had different responses to the same environment.
This paper presents the initial findings of ASHRAE research project RP-462, a field study of environmental conditions and occupant comfort in ten office buildings in the San Francisco Bay region. We made a total of 2342 visits to 304 participants during two seasons, collecting a full set of physical measurements and subjective responses at each visit. In this paper we describe the building environments and their conformity to the requirements of tire thermal standards, the distribution of thermal sensation responses, neutral and preferred temperatures, conditions of thermal acceptability, and gender and seasonal effects on comfort responses. A few of the results are as follows: 78.2% (winter) and 52.8% (summer) of the workstation measurements fell within the ASHRAE Standard 55-81 comfort zones; the higher summer comfort zone was judged as too warm based on several rating scales; neutral temperatures were 22.0°C (winter) and 22.6°C (summer), and preferred temperatures were 0.3-0.6°C cooler.
This paper describes the logic of a microprocessor-controlled thermostat termed 'comfortstat' to address the needs of temporary room occupants such as hotel guests while reducing energy consumption. The 'comfortstat' design grew out of a study of thermal control in a luxury hotel in San Francisco, California, USA. Hotel guests frequently arrive from widely disparate climates and have high expectation so of the thermal environment. Their short-term occupancy (for periods ranging from one day to several weeks) provides a unique challenge for thermal comfort control. We examined the hotel complaint log, collected detailed physical measurements of the thermal environment in typical hotel rooms, assessed the HVAC (heating, venting and air-conditioning) system capacity and response time, and surveyed 315 hotel guests over a five-month period. The results of this study led to the design of a thermostat control system (the 'thermostat') what would solve the most serious problems. The 'comfortstat' integrates an infrared occupancy sensor, door switch, radiant temperature sensor, and control logical to optimize room conditions while 'learning' about the occupant's preferred comfort zone. This paper focuses on how the joint requirements of the guests and the hotel management guided the design of the 'comfortstat' for increased occupant satisfaction and lower energy use in the hotel. The concepts are completely generic and could be applied to the design of comfort systems for other types of short term occupancy. We present control logic flowcharts and typical examples of hotel 'comfortstat' in response to data received from the physical environment and/or human input.
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