CAN SORBENT-BASED GAS PHASE AIR CLEANING FOR VOCS SUBSTITUTE FOR VENTILATION IN COMMERCIAL BUILDINGS?

This paper reviews current knowledge about the suitability of sorbent-based air cleaning for removing volatile organic compounds (VOCs) from the air in commercial buildings, as needed to enable reductions in ventilation rates and associated energy savings. The principles of sorbent air cleaning are introduced, criteria are suggested for sorbent systems that can counteract indoor VOC concentration increases from reduced ventilation, major findings from research on sorbent performance for this application are summarized, and related priority research needs are identified. Major conclusions include: sorbent systems can remove a broad range of VOCs with moderate to high efficiency, sorbent technologies perform effectively when challenged with VOCs at the low concentrations present indoors, and there is a large uncertainty about the lifetime and associated costs of sorbent air cleaning systems when used in commercial buildings for indoor VOC control. Suggested priority research includes: experiments to determine sorbent system VOC removal efficiencies and lifetimes considering the broad range and low concentration of VOCs indoors; evaluations of in-situ regeneration of sorbents; and an updated analysis of the cost of sorbent air cleaning relative to the cost of ventilation

A PILOT STUDY OF THE ACCURACY OF CO2 SENSORS IN COMMERCIAL BUILDINGS

Carbon dioxide (CO2) sensors are often deployed in commercial buildings to obtain CO2 data that are used to automatically modulate rates of outdoor air supply. The goal is to keep ventilation rates at or above design requirements and to save energy by avoiding ventilation rates exceeding design requirements. However, there have been many anecdotal reports of poor CO2 sensor performance in actual commercial building applications. This study evaluated the accuracy of 44 CO2 sensors located in nine commercial buildings to determine if CO2 sensor performance, in practice, is generally acceptable or problematic. CO2 measurement errors varied widely and were sometimes hundreds of parts per million. Despite its small size, this study provides a strong indication that the accuracy of CO2 sensors, as they are applied and maintained in commercial buildings, is frequently less than needed to measure typical values of maximum one-hour-average indoor-outdoor CO2 concentration differences with less than a 20percent error. Thus, we conclude that there is a need for more accurate CO2 sensors and/or better sensor maintenance or calibration procedures

Bostonia. Volume 15

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Meta-Analyses of the Associations of Respiratory Health Effectswith Dampness and Mold in Homes

The Institute of Medicine (IOM) of the National Academy of Sciences recently completed a critical review of the scientific literature pertaining to the association of indoor dampness and mold contamination with adverse health effects. In this paper, we report the results of quantitative meta-analysis of the studies reviewed in the IOM report. We developed point estimates and confidence intervals (CIs) to summarize the association of several respiratory and asthma-related health outcomes with the presence of dampness and mold in homes. The odds ratios and confidence intervals from the original studies were transformed to the log scale and random effect models were applied to the log odds ratios and their variance. Models were constructed both accounting for the correlation between multiple results within the studies analyzed and ignoring such potential correlation. Central estimates of ORs for the health outcomes ranged from 1.32 to 2.10, with most central estimates between 1.3 and 1.8. Confidence intervals (95%) excluded unity except in two of 28 instances, and in most cases the lower bound of the CI exceeded 1.2. In general, the two meta-analysis methods produced similar estimates for ORs and CIs. Based on the results of the meta-analyses, building dampness and mold are associated with approximately 30% to 80% increases in a variety of respiratory and asthma-related health outcomes. The results of these meta-analyses reinforce the IOM's recommendation that actions be taken to prevent and reduce building dampness problems

ACCURACY OF CO2 SENSORS

Are the carbon dioxide (CO2) sensors in your demand controlled ventilation systems sufficiently accurate? The data from these sensors are used to automatically modulate minimum rates of outdoor air ventilation. The goal is to keep ventilation rates at or above design requirements while adjusting the ventilation rate with changes in occupancy in order to save energy. Studies of energy savings from demand controlled ventilation and of the relationship of indoor CO2 concentrations with health and work performance provide a strong rationale for use of indoor CO2 data to control minimum ventilation rates1-7. However, this strategy will only be effective if, in practice, the CO2 sensors have a reasonable accuracy. The objective of this study was; therefore, to determine if CO2 sensor performance, in practice, is generally acceptable or problematic. This article provides a summary of study methods and findings ? additional details are available in a paper in the proceedings of the ASHRAE IAQ?2007 Conference8

Accuracy of CO2 sensors in commercial buildings: a pilotstudy

Carbon dioxide (CO{sub 2}) sensors are often deployed in commercial buildings to obtain CO{sub 2} data that are used to automatically modulate rates of outdoor air supply. The goal is to keep ventilation rates at or above code requirements, but to also to save energy by avoiding over ventilation relative to code requirements. However, there have been many anecdotal reports of poor CO{sub 2} sensor performance in actual commercial building applications. This study evaluated the accuracy of 44 CO{sub 2} sensors located in nine commercial buildings to determine if CO{sub 2} sensor performance, in practice, is generally acceptable or problematic. CO{sub 2} measurement errors varied widely and were sometimes hundreds of parts per million. Despite its small size, this study provides a strong indication that the accuracy of CO{sub 2} sensors used in commercial buildings is frequently less than is needed to measure peak indoor-outdoor CO{sub 2} concentration differences with less than a 20% error. Thus, we conclude that there is a need for more accurate CO{sub 2} sensors and/or better sensor maintenance or calibration procedures

Changing ventilation rates in U.S. offices: Implications for health, work performance, energy, and associated economics

This paper provides quantitative estimates of benefits and costs of providing different amounts of outdoor air ventilation in U.S. offices. For four scenarios that modify ventilation rates, we estimated changes in sick building syndrome (SBS) symptoms, work performance, short-term absence, and building energy consumption. The estimated annual economic benefits were $13 billion from increasing minimum ventilation rates (VRs) from 8 to 10 L/s per person,$38 billion from increasing minimum VRs from 8 to 15 L/s per person, and $33 billion from increasing VRs by adding outdoor air economizers for the 50$0.04 billion in annual energy-related benefits of decreasing minimum VRs from 8 to 6.5 L/s per person are very small compared to the projected annual costs of $12 billion. Benefits of increasing minimum VRs far exceeded energy costs while adding economizers yielded health, performance, and absence benefits with energy savings

Development and Field-Testing of a Study Protocol, including a Web-Based Occupant Survey Tool, for Use in Intervention Studies of Indoor Environmental Quality

We developed and pilot-tested an overall protocol for intervention studies to evaluate the effects of indoor environmental changes in office buildings on the health symptoms and comfort of occupants. The protocol includes a web-based survey to assess the occupant's responses, as well as specific features of study design and analysis. The pilot study, carried out on two similar floors in a single building, compared two types of ventilation system filter media. With support from the building's Facilities staff, the implementation of the filter change intervention went well. While the web-based survey tool worked well also, low overall response rates (21-34percent among the three work groups included) limited our ability to evaluate the filter intervention., The total number of questionnaires returned was low even though we extended the study from eight to ten weeks. Because another simultaneous study we conducted elsewhere using the same survey had a high response rate (>70percent), we conclude that the low response here resulted from issues specific to this pilot, including unexpected restrictions by some employing agencies on communication with occupants