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The energy and IAQ implications of varying prescribed minimum outdoor air ventilation rates (VRs) in California office buildings were estimated using the EnergyPlus building simulation software tool. Weighting factors were used to scale these model predictions to state wide estimates. Energy use predictions were then verified using surveyed California building energy end use data. Models predicted state wide office electricity use that was within 15% of reported electricity consumption from power utilities. The HVAC energy penalty of providing the current Title-24 VRs was approximately 6%, of the total HVAC energy use. Having economizers installed reduced average indoor formaldehyde exposure by 38% and lowered HVAC EUI by 20%. For California offices with economizers, 50% and 100% increases in Title-24 prescribed minimum VRs increased heating, ventilating, and air conditioning (HVAC) modeled energy use by 7.6% and 21.6%, respectively, while decreasing the annual average workplace formaldehyde exposure by 8.6% and 14.4%, respectively. Economizers increased VRs above the minimum 79% of the time lowering annual average concentrations of formaldehyde. Decreasing minimum VRs below the Title-24 rate would have smaller predicted effects on energy use and comparatively larger effects on formaldehyde concentrations. In buildings without economizers in many climate zones, increasing VRs up to 150% of the current Title-24 minimum would save HVAC energy and significantly reduce formaldehyde. A key conclusion is that raising future minimum VRs in California offices is unlikely to significantly improve time-averaged IAQ in buildings with economizers. Lowering future minimum VRs would be unlikely to deliver substantive energy savings.

Sixteen apartments serving low-income populations in three buildings were retrofit with the goal of simultaneously reducing energy consumption and improving indoor environmental quality (IEQ). Retrofit measures varied among apartments and included, among others, envelope sealing, installation of continuous mechanical ventilation systems, upgrading bathroom fans and range hoods, attic insulation, replacement of heating and cooling systems, and adding wall-mounted particle air cleaners. IEQ parameters were measured, generally for two one-week periods before and after the retrofits. The measurements indicate an overall improvement in IEQ conditions after the retrofits. Comfort conditions, bathroom humidity, and concentrations of carbon dioxide, acetaldehyde, volatile organic compounds, and particles generally improved. Formaldehyde and nitrogen dioxide levels decreased in the building with the highest concentrations, were unchanged in a second building, and increased in a third building. IEQ parameters other than particles improved more in apartments with continuous mechanical ventilation systems installed. In general, but not consistently, larger percent increases in air exchange rates were associated with larger percent decreases in indoor levels of the pollutants that primarily come from indoor sources.

This study examines the human health implications of natural ventilation in California office buildings. We modeled work-time exposures using field data on indoor and outdoor ozone and particulate matter from four case studies in naturally ventilated offices and published data from mechanically ventilated offices. We also modeled the amount of time that windows would be open in the naturally ventilated office and used the results to estimate the difference in pollutant exposures for occupants of naturally ventilated versus mechanically ventilated, air-conditioned offices. Based on published concentration–response equations, we estimated the incremental changes in health outcomes that resulted from the difference in exposures for occupants in the two types of offices. We also estimated the differences in sick building symptom rates based on symptom prevalence rates in naturally ventilated and air-conditioned offices. Finally, we developed first-order estimates of the health-related costs and benefits of retrofitting 10 percent of California's current office space to use natural ventilation. Findings included an increase in annual health-related costs from increased exposure to ozone and particulate matter of between $130 million and $207 million, and a reduction in sick building syndrome symptom costs, valued between $4.3 million and $11.5 million. Our estimates have a high degree of uncertainty and exclude potentially significant health-related costs and benefits of both naturally ventilated and air-conditioned buildings. Nonetheless, these estimates indicate that health-related costs of natural ventilation are significant and warrant further study. We also explore several mitigation options that could limit the health and economic impacts of natural ventilation.

The current focus on building energy retrofit provides an opportunity to simultaneously improve indoor environmental quality (IEQ). Toward this end, we developed a protocol for selecting packages of retrofits that both save energy and improve IEQ in apartments. The protocol specifies the methodology for selecting retrofits from a candidate list while addressing expected energy savings, IEQ impacts, and costs in an integrated manner. Interviews, inspections and measurements are specified to collect the needed input information. The protocol was applied to 17 apartments in three buildings in two different climates within California. Diagnostic measurements and surveys conducted before and after retrofit implementation indicate enhanced apartment performance.

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% of the office floor area that currently lacks economizers. The estimated $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.

This study explores the potential environmental and energy benefits of using activated carbon fiber (ACF) filters for air cleaning in HVAC systems. The parallel aims for the air cleaning system were to enable reduced indoor exposures to volatile organic compounds (VOCs) and to simultaneously allow reduced rates and energy consumption for outdoor air ventilation. We evaluated the use of ACF media to adsorb VOCs from indoor air during repeated simulated 12-h to 24-h periods of occupancy. In a cyclic regeneration process, VOCs were desorbed from the ACF media and vented outdoors to enable the next cycle of air cleaning. The VOC removal efficiency of the ACF media was measured using a 9.5-cm 2 ACF specimen exposed to a mixture of VOCs that included toluene, benzene, o-xylene, 1-butanol, limonene, undecane and formaldehyde at 29 °C and 30% relative humidity. The concentrations of these model pollutants upstream of the ACF media were in the range 20–30 ppb, to simulate realistic conditions. Velocities through the ACF media were typical of those in normal particle filter systems (∼0.5 m s −1 ). Initial tests were conducted to develop a modified multi-component Freundlich isotherm and estimate the maximum adsorption capacity of the media, which was determined to be 90 mg VOC per gram of ACF. Three different ACF regeneration methods were explored using relatively cleaner outdoor air under ambient conditions, with this air humidified, and with the filter heated. It was found that heating the ACF media to ∼150 °C by circulation of a DC current through the fibers for a short period (15 min) yielded the best VOC removal results, allowing for subsequent consistent removal efficiencies of 70–80% for most VOCs. Regeneration with unheated outdoor air was also effective and used less energy (subsequent removal efficiency was 50–60% for most VOCs). ACF did not perform as well in eliminating formaldehyde, for which a maximum removal of 25–30% was achieved with heated regeneration. A mass balance model indicated that the combination of ACF air cleaning and a 50% reduction in ventilation will decrease indoor concentrations of VOCs by 60%–80% and reduce formaldehyde concentrations by 12%–40%. Energy modeling indicated the potential to reduce the energy required for heating and cooling of ventilation air by 35% to almost 50%.

Appl. Catal. B – Environmental, 2011 Quantitative room-temperature mineralization of airborne formaldehyde using manganese oxide catalysts Meera A. Sidheswaran, Hugo Destaillats, Douglas P. Sullivan, Joern Larsen and William J. Fisk Environmental Energy Technologies Division June 2011

Prior research suggests that chemical processes taking place on the surface of particle filters employed in buildings may lead to the formation of harmful secondary byproducts. We investigated ozone reactions with fiberglass, polyester, cotton/polyester and polyolefin filter media, as well as hydrolysis of filter media additives. Studies were carried out on unused media, and on filters that were installed for 3 months in buildings at two different locations in the San Francisco Bay Area. Specimens from each filter media were exposed to {approx}150 ppbv ozone in a flow tube under a constant flow of dry or humidified air (50percent RH). Ozone breakthrough was recorded for each sample over periods of {approx}1000 min; the ozone uptake rate was calculated for an initial transient period and for steady-state conditions. While ozone uptake was observed in all cases, we did not observe significant differences in the uptake rate and capacity for the various types of filter media tested. Most experiments were performed at an airflow rate of 1.3 L/min (face velocity = 0.013 m/s), and a few tests were also run at higher rates (8 to 10 L/min). Formaldehyde and acetaldehyde, two oxidation byproducts, were quantified downstream of each sample. Those aldehydes (m/zmore » 31 and 45) and other volatile byproducts (m/z 57, 59, 61 and 101) were also detected in real-time using Proton-Transfer Reaction - Mass Spectrometry (PTR-MS). Low-ppbv byproduct emissions were consistently higher under humidified air than under dry conditions, and were higher when the filters were loaded with particles, as compared with unused filters. No significant differences were observed when ozone reacted over various types of filter media. Fiberglass filters heavily coated with impaction oil (tackifier) showed higher formaldehyde emissions than other samples. Those emissions were particularly high in the case of used filters, and were observed even in the absence of ozone, suggesting that hydrolysis of additives, rather than ozonolysis, is the main formaldehyde source in those filters. Emission rates of formaldehyde and acetaldehyde were not found to be large enough to substantially increase indoor concentrations in typical building scenarios. Nevertheless, ozone reactions on HVAC filters cannot be ignored as a source of low levels of indoor irritants.« less

This paper presents major findings of a field study on the performance of five thermal distribution systems in four large commercial buildings. The five systems studied are typical single-duct or dual-duct constant air volume (CAV) systems and variable air volume (VAV) systems, each of which serves an office building or a retail building with floor area over 2000 m 2 . The air leakage from ducts is reported in terms of effective leakage area (ELA) at 25 Pa reference pressure, the ASHRAE-defined duct leakage class C L , and air leakage ratios. The specific ELAs ranged from 0.7 to 12.9 cm 2 /m 2 of duct surface area, and from 0.1 to 7.7 cm 2 /m 2 of floor area served. The ASHRAE-defined duct leakage classes ranged from 34 to 606 for the five systems and systems sections tested. The air leakage ratios were estimated to be up to approximately one-third of the fan-supplied airflow in the constant air volume systems. The specific ELAs and leakage classes indicated that air leakage in large commercial duct systems varied significantly from system to system, and from system section to system section even within the same thermal distribution system. Overall, the duct systems measured were much leakier than the ductwork specified as “unsealed ducts” by ASHRAE. On the other hand, thermal losses from supply ducts induced by conduction (including convection and radiation) were significant, on the scale that was comparable to the losses induced by air leakage in the duct systems. The energy losses induced by leakage and conduction suggested that there exist significant energy savings potentials from duct sealing and duct insulation practice in large commercial buildings.

Human chromosome 2q33 is an immunologically important region based on the linkage of numerous autoimmune diseases to the CTLA4 locus. Here, we sequenced and assembled 2q33 bacterial artificial chromosome (BAC) clones, resulting in 381,403 bp of contiguous sequence containing genes encoding a NADH:ubiquinone oxidoreductase, the costimulatory receptors CD28, CTLA4, and ICOS, and a HERV-H type endogenous retrovirus located 366 bp down-stream of ICOS in the reverse orientation. Genomic microarray expression analysis using differentially activated T-cell RNA against a subcloned CTLA4/ICOS BAC library revealed upregulation of CTLA4 and ICOS sequences, plus antisense ICOS transcripts generated by the HERV-H, suggesting a potential mechanism for ICOS regulation. We identified four non-linked, polymorphic, simple repetitive sequence elements in this region, which may be used to delineate genetic effects of ICOS and CTLA4 in disease populations. Comparative genomic analysis of mouse genomic Icos sequences revealed 60% sequence identity in the 5′ UTR and regions between exon 2 and the 3′ UTR, suggesting the importance of ICOS gene function.

Pulses of ecdysteroids direct Drosophila through its life cycle by activating stage- and tissue-specific genetic regulatory hierarchies. Here we show that an orphan nuclear receptor, DHR78, functions at the top of the ecdysteroid regulatory hierarchies. Null mutations in DHR78 lead to lethality during the third larval instar with defects in ecdysteroid-triggered developmental responses. Consistent with these phenotypes, DHR78 mutants fail to activate the mid-third instar regulatory hierarchy that prepares the animal for metamorphosis. DHR78 protein is bound to many ecdysteroid-regulated puff loci, suggesting that DHR78 directly regulates puff gene expression. In addition, ectopic expression of DHR78 has no effects on development, indicating that its activity is regulated posttranslationally. We propose that DHR78 is a ligand-activated receptor that plays a central role in directing the onset of Drosophila metamorphosis.

The short persistence of some foreign gene products remains as a post-translational barrier to effectively expressing desirable traits in transgenic plants. We hypothesized that localization of these proteins within the nucleus may enhance their stability relative to what is possible in the cytosol, a much more common choice as final destination. Here we show that directing the bacterial reporter β -glucuronidase (GUS) to the nucleus using a nuclear localization sequence (NLS) from simian virus 40 (SV40) resulted in an increase in accumulation of approximately 50% when expressed transiently in tobacco protoplasts. Results from assays designed to quantify enzymatic activity or GUS-specific RNA strongly suggested that the increased accumulation was due to enhanced stability. Stable expression of the same nuclear-targeted enzyme in transgenic tobacco plants generally resulted in higher (up to ten-fold) activity levels and a similar argument of enhanced stability as an explanation for these data is discussed.

To study the effects of atmospheric pressure fluctuations on the entry of radon and soil-gas contaminants into houses, we have simultaneously measured the changes in atmospheric pressure and the gas flow rate between the interior of an experimental basement structure and the underlying soil. Atmospheric pressure fluctuations draw soil gas into the experimental basement without the indoor-outdoor pressure differences commonly associated with advective entry of soil-gas contaminants. The soil-gas flow rate induced by a change in atmospheric pressure depends on both the characteristic response time of the soil and the time-rate-of-change of the atmospheric pressure fluctuation. Spectral analysis indicates that relatively low-frequency fluctuations in atmospheric pressure are the most important for driving soil-gas into and out the of the experimental structure; more than 60% of the total power of the soil-gas flow spectrum occurs at frequencies less than 100 d −1 . A transient finite-element model based on Darcy's law correctly predicts both the dynamics and the magnitude of the observed gas flow. Atmospheric pressure fluctuations may increase the long-term radon entry rate into the experimental structure by as much as 0.2 Bq s −1 , which is more than twice the measured diffusive entry rate into the structure and comparable to the radon entry rate driven by a − 0.4 Pa, steady indoor-outdoor pressure difference.

Active sub-slab depressurization (SSD) systems are an effective means of reducing indoor radon concentrations in residential buildings. However, energy is required to operate the system fan and to heat or cool the resulting increased building ventilation. We present regional and national estimates of the energy requirements, operating expenses and CO 2 emissions associated with using SSD systems at saturation (i.e. in all US homes with radon concentrations above the EPA remediation guideline and either basement or slab-on-grade construction). The primary source of uncertainty in these estimates is the impact of the SSD system on house ventilation rate. Overall, individual SSD system operating expenses are highest in the Northeast and Midwest at about $99 y −1 , and lowest in the South and West at about $66 y −1 . The fan consumes, on average, about 40% of the end-use energy used to operate the SSD system and accounts for about 60% of the annual expense. At saturation, regional impacts are largest in the Midwest because this area has a large number of mitigable houses and a relatively high heating load. We estimate that operating SSD systems in US houses, where it is both appropriate and possible (about 2,6 million houses), will annually consume 1.7 × 10 4 (6.4 × 10 3 to 3.9 × 10 4 ) TJ of end-use energy, cost $230 (130 to 400) million (at current energy prices), and generate 2.0 × 10 9 (1.2 × 10 9 to 3.5 × 10 9 ) kg of CO 2 . Passive or energy efficient radon mitigation systems currently being developed offer opportunities to substantially reduce these impacts.

Finish-line imaging, in which DNA or other macromolecules are detected after electrophoresis for a constant distance, usually improves resolution compared to snapshot imaging, in which molecules are electrophoresed for a constant time in an apparatus of comparable dimensions. Resolving power, which is an objective measure of the ability of different separatory methods to detect closely spaced molecular species, can be used to compare directly the performance of systems employing both snapshot and finish-line imaging [E. A. Ribeiro and J. C. Sutherland, Anal. Biochem. 210, 378-388 (1993)]. Experimentally determined values of resolving power are influenced both by the method of imaging (snapshot vs finish-line) and by instrument-specific factors that affect resolution. Previous comparisons of the resolving power obtained with finish-line and snapshot imaging involved data sets acquired by different instruments with different instrumental resolutions. To reduce the influence of instrumental effects, we constructed a scanning laser fluorometer that can measure both snapshot and finish-line images of fluorochrome-labeled DNA. Snapshot and finish-line images of a DNA sample containing HaeII restriction fragments of the DNA from bacteriophage T7, which range in length from 474 to 6514 base pairs, were obtained under otherwise identical electrophoretic conditions. Snapshot and finish-line imaging give similar resolving powers for DNA molecules up to about 1.5 kbp long. For both imaging modes, maximum resolving power was achieved for DNA molecules between 2 and 3 kbp in length. For larger DNA molecules, finish-line imaging provided higher resolving power. The ratio of the resolving power of finish-line images to that of snapshot images increased monotonically as a function of DNA length. For the longest restriction fragments studied (6514 bp), the resolving power for finish-line images exceeded that of snapshot images by about 50%.

Radon is the largest source of risk to human health caused by an indoor pollutant in the industrial countries. Subslab ventilation (SSV) is one of the most effective and common methods of reducing indoor radon concentrations in houses with a basement. In this paper, the impact of SSV on the air exchange rate is quantified, through numerical modeling of a prototype house with basement for a range of permeabilities of soil and subslab aggregate and various sizes of the cracks in the basement floor. We show that a SSV system can increase the air exchange rate by as much as a factor of 4.5. Then the energy and capital costs of a subslab depressurization (SSD) system are compared with those of direct ventilation of the basement which is required to lower the indoor radon concentration to an acceptable level for a Chicago climate. We show that (1) an exhaust ventilation cannot significantly reduce the indoor radon concentration and may even increase it, and (2) a balanced ventilation with heat recovery is only effective for low premitigation radon concentrations. However, both SSV and balanced ventilation systems are probably too expensive to be recommended in houses with low premitigation radon concentrations. A SSD system is the most cost-effective technique for reduction of high radon concentrations.

The worldwide effort to transform an ever-increasing number of plant species with high efficiency has resulted in a number of promising gene transfer systems that continue to become more refined. Although Agrobacterium -mediated transformation remains the method of choice, alternative methods such as electroporation and particle bombardment have been developed in order to circumvent poorly understood biological barriers which prevents its application to certain plants, most notably monocots. In addition to the transfer of foreign DNA into plant cells, another aspect critical to any transformation method is the ability to conveniently and specifically select and regenerate transgenic cells. This prerequisite has spurred the development of gene transfer techniques which utilize organized, regenerable tissue explants as well as lead to the employment of a variety of genes that encode resistance to antibiotics or herbicides. The emerging ability to deliberately and specifically regulate gene expression within higher plants is an area of critical importance for many experimental or improvement strategies which involve gene transfer Numerous gene promoters are now available that can regulate transcription spatially, temporally and quantitatively while molecular knowledge which details these mechanisms of regulation continues to accrue. Modification of post-transcriptional processes is also becoming an increasingly important engineering tool as the function of antisense genes, translational enhancers and knowledge of codon usage frequencies becomes better elucidated. Whereas these two general areas of gene transfer and gene expression have lead to a deeper understanding of plant biology, this review limits its focus to those aspects currently relevant to crop improvement.

Residential energy consumption can be decreased if air infiltration is reduced by constructing houses more tightly. In some cases, however, reduced air infiltration can lead to problems with indoor air quality (e.g., excess humidity and high levels of indoor-generated air contaminants). One solution to this problem is to install a residential air-to-air heat exchanger. The heat exchanger provides a controlled supply of ventilation which counteracts the adverse effects of reduced infiltration. In addition, the heat exchanger recovers much of the energy that would normally be lost when ventilation occurs by air infiltration. Thus, by employing heat exchangers in low-infiltration houses, it is possible to save energy without sacrificing indoor air quality. This paper discusses the performance of residential heat exchangers and summarizes results from tests of several models. It also compares the energy consumed, during the heating season, in low-infiltration houses with heat exchangers, with the energy consumed in typical houses in four cities throughout the United States. For each city, a cost-benefit analysis is performed from the point of view of a home-owner. Houses with natural gas, oil, and electrical heating systems are considered. Our analysis indicates that the energy required to heat ventilation air in homes employing heat exchangers is 5.3 – 18.0 GJ less than the energy required to heat ventilation air in typical homes. In homes with heat exchangers, the heat exchanger's fan system required 2.2 – 3.6 GJ of electrical energy during the heating season. The net present benefit for homes employing heat exchangers, when compared with typical homes, ranged from —$1350 to +$2400 and discounted payback periods ranged from five to over 30 years. The cost-effectiveness of employing heat exchangers was found to be highly affected by climate, type of heating fuel, heat exchanger performance, and ventilation rate.

The Bonneville Power Administration (BPA) has proposed a ten year program to encourage the weatherization of electrically heated homes in the Pacific Northwest. The purpose of this program is to reduce residential electrical energy demand for space heating. If air infiltration rates are reduced by employing house tightening measures, indoor air quality mitigation measures may be required in residences with significant sources of indoor air contaminants. The use of residential air-to-air heat exchangers has been proposed as a possible strategy to assure that indoor air quality is not substantially degraded by house tightening. We examine the energy impact and cost effectiveness of heat exchanger utilization in tightened homes in the BPA region. Significant energy savings are predicted if homes are tightened and heat exchangers are utilized. From the homeowner's perspective, the results of our economic analysis indicate that, at the relatively low residential electric rates in the BPA region, the use of heat exchangers in existing homes that are tightened is not economically viable. On the other hand, from the utility perspective, it may be cost effective to use heat exchangers in the weatherization program if the marginal cost to the utility is compared with the cost of conserved energy.