52 research outputs found
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A Prototype Toolkit For Evaluating Indoor Environmental Quality In Commercial Buildings
Measurement of building environmental parameters is often complex, expensive, and not easily proceduralized in a manner that covers all commercial buildings. Evaluating building indoor environmental quality performance is therefore not standard practice. This project developed a prototype toolkit that addressed existing barriers to widespread indoor environmental quality performance evaluation. A toolkit with both hardware and software elements was designed for practitioners around the indoor environmental quality requirements of the American Society of Heating, Refrigeration and Air Conditioning Engineers / Chartered Institution of Building Services / United States Green Building Council Performance Measurement Protocols. This unique toolkit was built on a wireless mesh network with a web-based data collection, analysis, and reporting application. The toolkit provided a fast, robust deployment of sensors, real-time data analysis, Performance Measurement Protocol-based analysis methods and a scorecard and report generation tools. A web-enabled Geographic Information System-based metadata collection system also reduced field-study deployment time. The toolkit was evaluated through three case studies, which were discussed in this report
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Evaluation of the Repeatability of the Delta Q Duct Leakage Testing TechniqueIncluding Investigation of Robust Analysis Techniques and Estimates of Weather Induced Uncertainty
The DeltaQ test is a method of estimating the air leakage from forced air duct systems. Developed primarily for residential and small commercial applications it uses the changes in blower door test results due to forced air system operation. Previous studies established the principles behind DeltaQ testing, but raised issues of precision of the test, particularly for leaky homes on windy days. Details of the measurement technique are available in an ASTM Standard (ASTM E1554-2007). In order to ease adoption of the test method, this study answers questions regarding the uncertainty due to changing weather during the test (particularly changes in wind speed) and the applicability to low leakage systems. The first question arises because the building envelope air flows and pressures used in the DeltaQ test are influenced by weather induced pressures. Variability in wind induced pressures rather than temperature difference induced pressures dominates this effect because the wind pressures change rapidly over the time period of a test. The second question needs to answered so that DeltaQ testing can be used in programs requiring or giving credit for tight ducts (e.g., California's Building Energy Code (CEC 2005)). DeltaQ modeling biases have been previously investigated in laboratory studies where there was no weather induced changes in envelope flows and pressures. Laboratory work by Andrews (2002) and Walker et al. (2004) found biases of about 0.5% of forced air system blower flow and individual test uncertainty of about 2% of forced air system blower flow. The laboratory tests were repeated by Walker and Dickerhoff (2006 and 2008) using a new ramping technique that continuously varied envelope pressures and air flows rather than taking data at pre-selected pressure stations (as used in ASTM E1554-2003 and other previous studies). The biases and individual test uncertainties for ramping were found to be very close (less than 0.5% of air handler flow) to those found in for the pressure station approach. Walker and Dickerhoff also included estimates of DeltaQ test repeatability based on the results of field tests where two houses were tested multiple times. The two houses were quite leaky (20-25 Air Changes per Hour at 50Pa (0.2 in. water) (ACH50)) and were located in the San Francisco Bay area. One house was tested on a calm day and the other on a very windy day. Results were also presented for two additional houses that were tested by other researchers in Minneapolis, MN and Madison, WI, that had very tight envelopes (1.8 and 2.5 ACH50). These tight houses had internal duct systems and were tested without operating the central blower--sometimes referred to as control tests. The standard deviations between the multiple tests for all four houses were found to be about 1% of the envelope air flow at 50 Pa (0.2 in. water) (Q50) that led to the suggestion of this as a rule of thumb for estimating DeltaQ uncertainty. Because DeltaQ is based on measuring envelope air flows it makes sense for uncertainty to scale with envelope leakage. However, these tests were on a limited data set and one of the objectives of the current study is to increase the number of tested houses. This study focuses on answering two questions: (1) What is the uncertainty associated with changes in weather (primarily wind) conditions during DeltaQ testing? (2) How can these uncertainties be reduced? The first question is addressing issues of repeatability. To study this five houses were tested as many times as possible over a day. Weather data was recorded on-site--including the local windspeed. The result from these five houses were combined with the two Bay Area homes from the previous studies. The variability of the tests (represented by the standard deviation) is the repeatability of the test method for that house under the prevailing weather conditions. Because the testing was performed over a day a wide range of wind speeds was achieved following typical diurnal variations of low wind in the early morning and greatest winds in the late afternoon/early evening. Typically about ten tests were performed in each house. To answer the second question, different data analysis techniques were investigated that looked at averaging techniques, elimination of outliers, limiting leak pressures, etc. in order to minimize the influence of changing wind conditions during the test. The objective was to find a reasonable compromise between test precision and robustness--because many of the changes to the analysis to make the test more robust limit its ability to examine wide ranges of pressures and leakage flows. A secondary goal of this study is to show that DeltaQ uncertainties are acceptable for testing low leakage systems. Therefore houses with low duct leakage were deliberately chosen to be tested
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Effects of air infiltration on the effective thermal conductivity of internal fiberglass insulation and on the delivery of thermal capacity via ducts
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Field Study of Capitol Area East End Complex (CAEEC) Sacramento, California
The energy and comfort performance of buildings using underfloor air distribution (UFAD) has been of interest, with some contention, in the building industry for many years. It is not often that an opportunity to address that question directly appears. This project represented such an opportunity to compare and contrast two similarly designed buildings in the same climate and co-located near one another, both occupied by California state employees, one with a UFAD system (B225) and the other with an overhead (OH) variable air volume (VAV) system (B172). At the outset there was hope that we could settle the question definitively due to the highly instrumented systems in these buildings that afforded an opportunity to use measured data for the comparison. This report contains a detailed description of the measured data and simulated analyses used to compare the energy performance of UFAD vs. OH systems, and a summary of the post occupancy evaluations (POE) used to study and compare the occupant satisfaction and indoor environmental quality (IEQ) of both buildings. In addition, we report on field measurements conducted in B225 to investigate two key performance issues with UFAD systems: (1) room air stratification and (2) temperature gain in underfloor plenums. The key findings from the study are listed here: • The measured energy performance data indicates improved efficiency for the UFAD system (B225) vs. the OH system (B172), as annual cooling energy is 31% higher and total annual fan energy is 50% higher for B172 compared to B225. • To account for all major design and operating differences between the buildings, we developed an alternative analysis method based on estimating the impact on B172 energy performance as if it was configured and equipped with central system equipment similar to B225; aka “apples to apples” comparison. When this “apples to apples” comparison method was applied, the total annual HVAC energy use (including cooling, heating, and fans) for OH (B172) is 20% higher than UFAD (B225) and total annual whole building energy use for B172 is 8% higher than B225. • Based on the calculated Energy Star ratings, both B225 and B172 demonstrate excellent energy performance overall. B225 showed a very high site Energy Star rating of 98 and the Energy Star rating for the B171-174 complex (B172 could not be calculated separately) was 91, both well above the 75 required to receive the Energy Star label. • The final POE surveys conducted during October 2007 in the two buildings found that the satisfaction ratings were generally positive and very nearly the same for most of the categories. An important lesson learned from the repeated surveys in B225 between 2003 and 2007 was the value of continuous commissioning of a building’s HVAC system. Efforts by building operations staff and the research team led to an improved understanding of the unique features of the UFAD system, and as a result, greater occupant satisfaction with the quality of the indoor environment in B225
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Air leakage test report: EPA region 8 headquarters, Denver, CO
On May 16-18, 2008, CBE researchers working in collaboration with key personnel from Engineered Interiors Group (EIG), Opus NW Management/GPT, and the Environmental Protection Agency (EPA), conducted air leakage tests in the EPA Region 8 Headquarters Building in Denver, CO. There were two primary objectives for this testing:1. Determine the characteristic air flow leakage rate from the underfloor air distribution system on the 7th floor, and2. Using alternative testing methods assess the overall accuracy and effectiveness of the GSA leak testing protocol.We begin this report with a description of the EPA building, a background description of the basic leakage types, discussion of airflow measurement methods, and a description of the GSA protocol. This is followed with a section that documents the results of all testing accomplished and includes discussions of these results and their implications for the GSA protocol. In the Appendices, we provide a detailed documentation of the test and calibration procedures and reprint the GSA Protocol
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Air leakage test report: EPA region 8 headquarters, Denver, CO
On May 16-18, 2008, CBE researchers working in collaboration with key personnel from Engineered Interiors Group (EIG), Opus NW Management/GPT, and the Environmental Protection Agency (EPA), conducted air leakage tests in the EPA Region 8 Headquarters Building in Denver, CO. There were two primary objectives for this testing:1. Determine the characteristic air flow leakage rate from the underfloor air distribution system on the 7th floor, and2. Using alternative testing methods assess the overall accuracy and effectiveness of the GSA leak testing protocol.We begin this report with a description of the EPA building, a background description of the basic leakage types, discussion of airflow measurement methods, and a description of the GSA protocol. This is followed with a section that documents the results of all testing accomplished and includes discussions of these results and their implications for the GSA protocol. In the Appendices, we provide a detailed documentation of the test and calibration procedures and reprint the GSA Protocol
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Field Study of Capitol Area East End Complex (CAEEC) Sacramento, California
The energy and comfort performance of buildings using underfloor air distribution (UFAD) has been of interest, with some contention, in the building industry for many years. It is not often that an opportunity to address that question directly appears. This project represented such an opportunity to compare and contrast two similarly designed buildings in the same climate and co-located near one another, both occupied by California state employees, one with a UFAD system (B225) and the other with an overhead (OH) variable air volume (VAV) system (B172). At the outset there was hope that we could settle the question definitively due to the highly instrumented systems in these buildings that afforded an opportunity to use measured data for the comparison. This report contains a detailed description of the measured data and simulated analyses used to compare the energy performance of UFAD vs. OH systems, and a summary of the post occupancy evaluations (POE) used to study and compare the occupant satisfaction and indoor environmental quality (IEQ) of both buildings. In addition, we report on field measurements conducted in B225 to investigate two key performance issues with UFAD systems: (1) room air stratification and (2) temperature gain in underfloor plenums. The key findings from the study are listed here: • The measured energy performance data indicates improved efficiency for the UFAD system (B225) vs. the OH system (B172), as annual cooling energy is 31% higher and total annual fan energy is 50% higher for B172 compared to B225. • To account for all major design and operating differences between the buildings, we developed an alternative analysis method based on estimating the impact on B172 energy performance as if it was configured and equipped with central system equipment similar to B225; aka “apples to apples” comparison. When this “apples to apples” comparison method was applied, the total annual HVAC energy use (including cooling, heating, and fans) for OH (B172) is 20% higher than UFAD (B225) and total annual whole building energy use for B172 is 8% higher than B225. • Based on the calculated Energy Star ratings, both B225 and B172 demonstrate excellent energy performance overall. B225 showed a very high site Energy Star rating of 98 and the Energy Star rating for the B171-174 complex (B172 could not be calculated separately) was 91, both well above the 75 required to receive the Energy Star label. • The final POE surveys conducted during October 2007 in the two buildings found that the satisfaction ratings were generally positive and very nearly the same for most of the categories. An important lesson learned from the repeated surveys in B225 between 2003 and 2007 was the value of continuous commissioning of a building’s HVAC system. Efforts by building operations staff and the research team led to an improved understanding of the unique features of the UFAD system, and as a result, greater occupant satisfaction with the quality of the indoor environment in B225
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Low pressure air-handling system leakage in large commercial buildings: Diagnosis, prevalence, and energy impacts
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