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Highlights • The natural ventilation reduction varies from 5% to 70% across the US. • Most cities have less than 20% reduction except for four cities in the US. • PM2.5 is the most significant outdoor air pollutant compared to PM10 and Ozone. • We have developed an advanced indoor air pollutant control with emulators. Abstract Natural ventilation has emerged as a desirable feature of sustainable buildings given its potential positive impact on building energy performance and amenities for occupants. In some circumstances, natural ventilation can provide a higher ventilation rate compared to mechanical ventilation, thus improving the air quality of indoor space, resulting in lower indoor carbon dioxide and volatile organic compound concentrations. However, this increased ventilation rate also raises the issue of increased indoor pollutant concentration from outdoor sources, which has been proven to significantly affect occupant health. In this paper, we investigate the influence of three major outdoor air pollutants, PM2.5, PM10, and ozone, on natural ventilation usage across 12 major US cities and their corresponding climate zones utilizing the outdoor air pollutant records from the US Environmental Protection Agency. Firstly, a descriptive statistics study presents a general description of air pollutant records in these investigated cities and climate zones. Then two natural ventilation operation scenarios (considering outdoor air pollutants vs. not) are developed and compared to explicitly show the expected natural ventilation reduction in these areas. The investigation results indicate that the most polluted area for natural ventilation is Los Angeles (with a projected 70% reduction), followed by Chicago (approximately 40% reduction), and then Atlanta and San Francisco (20–30% reduction for each). The natural ventilation reduction caused by outdoor air pollutants ranges from 5% to 20% in all other tested cities. Among the three pollutants (PM2.5, PM10, and ozone) we investigated, the influence of PM2.5 consistently emerges as the most critical to consider, while the impact of PM10 is typically trivial. The influence of ozone is not obvious in most cases. Nevertheless, in certain cases, its influence is non-negligible when natural ventilation is utilized. This study aims to provide a general guideline for decision makers to consider the influence of outdoor air quality on natural ventilation usage when adopting natural ventilation in different US locations. The results also confirmed the outdoor air pollutants, especially PM2.5, as a significant factor to consider in the natural ventilation design to shield the occupant from excessive air pollutant exposure. [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated a potential reduction in cooling load and improvement in comfort from the implementation of night ventilation. This paper describes the performance, in terms of indoor environmental conditions, of three buildings from both the U.S. and India that use night ventilation as their primary cooling method. The research methods used the following approach: (1) Assess the cooling strategy in relation to the adaptive comfort model; (2) Develop a hybrid model, using both first principle equations and the collected data, to predict the instantaneous air and mass temperatures within each building and use the model to assess performance of the cooling strategy; (3) Determine an optimized ventilation control strategy for each building to minimize energy and maintain comfortable temperatures. (4) Develop a statistical model using collected data to predict the window opening pattern for occupants of a building using natural night ventilation. The study yielded the following results: (1) The buildings in the mild climate are successfully keeping the indoor temperature low, but also tend to be overcooling; (2) The night ventilation strategy has very little impact on indoor conditions of the buildings in the mild climate; (3) The impact of night ventilation is less significant when there is low internal loads and heavy mass; (4) The building in the hot and humid climate is keeping the indoor temperature within the comfort bounds for 88% of the year; (5) The night ventilation strategy has advantageous impact on indoor conditons of the building in the hot and humid climate, but not enough to cool the space on its own; (6) Model predictive control has the potential to further improve the performance of night ventilation. (7) Window opening behavior for the building using natural night ventilation is most heavily dependent on indoor air temperature and mass temperature. [ABSTRACT FROM AUTHOR]

This study evaluates the energy patterns of 137 individual plug loads (desktops, laptops, monitors, and task lights) collected in a California office building over two years, and the effects of a behavior-based intervention on a subset of these devices to reduce plug load energy consumption. An analysis of the data reveals that desktops consume the most power per person and demonstrate the widest range of power consumption, and that occupants are more likely to turn equipment off before a longer break from the office than overnight during the week. Much of the literature on reducing commercial plug loads is focused on technology-based solutions, while the literature on changing occupant behavior is focused on residential occupants. Multiple studies show that non-financial incentives, such as games, can motivate behavior change. An online sustainability game, Cool Choices, was initiated on-site with 30 occupants, where players competed on teams to earn points for completing resource-saving actions. The analysis revealed that because occupants were already engaging in relevant energy saving behaviors (e.g. turning equipment off at the end of the day), there was limited opportunity for further behavior-based reductions. This study highlights the need for additional research in commercial buildings examining how to motivate occupant behavior change through non-financial incentives. [ABSTRACT FROM AUTHOR]

Recently accepted revisions to ASHRAE Standard 55—thermal environmental conditions for human occupancy, include a new adaptive comfort standard (ACS) that allows warmer indoor temperatures for naturally ventilated buildings during summer and in warmer climate zones. The ACS is based on the analysis of 21,000 sets of raw data compiled from field studies in 160 buildings located on four continents in varied climatic zones. This paper summarizes this earlier adaptive comfort research, presents some of its findings for naturally ventilated buildings, and discusses the process of getting the ACS incorporated into Standard 55. We suggest ways the ACS could be used for the design, operation, or evaluation of buildings, and for research applications. We also use GIS mapping techniques to examine the energy-savings potential of the ACS on a regional scale across the US. Finally, we discuss related new directions for researchers and practitioners involved in the design of buildings and their environmental control systems. [Copyright &y& Elsevier]

Growth in energy use for indoor cooling tripled between 1990 and 2016 to outpace any other end use in buildings. Part of this energy demand is wasted on excessive cooling of offices, a practice known as overcooling. Overcooling has been attributed to poorly designed or managed air-conditioning systems with thermostats that are often set below recommended comfort temperatures. Prior research has reported lower thermal comfort for women in office buildings, but there is insufficient evidence to explain the reasons for this disparity. We use two large and independent datasets from US buildings to show that office temperatures are less comfortable for women largely due to overcooling. Survey responses show that uncomfortable temperatures are more likely to be cold than hot regardless of season. Crowdsourced data suggests that overcooling is a common problem in warm weather in offices across the US. The associated impacts of this pervasive overcooling on well-being and performance are borne predominantly by women. The problem is likely to increase in the future due to growing demand for cooling in increasingly extreme climates. There is a need to rethink the approach to air-conditioning office buildings in light of this gender inequity caused by overcooling. [ABSTRACT FROM AUTHOR]

• A large thermal comfort database validated the ASHRAE 55–2017 adaptive model. • Adaptive comfort is driven more by exposure to indoor climate, than outdoors. • Air movement and clothing account for approximately 1/3 of the adaptive effect. • Analyses supports the applicability of adaptive standards to mixed-mode buildings. • Air conditioning practice should implement adaptive comfort in dynamic AC setpoints. The recent release of the largest database of thermal comfort field studies (ASHRAE Global Thermal Comfort Database II) presents an opportunity to perform a quality assurance exercise on the first generation adaptive comfort standards (ASHRAE 55 and EN15251). The analytical procedure used to develop the ASHRAE 55 adaptive standard was replicated on 60,321 comfort questionnaire records with accompanying measurement data. Results validated the standard's current adaptive comfort model for naturally ventilated buildings, while suggesting several potential nudges relating to the adaptive comfort standards, adaptive comfort theory, and building operational strategies. Adaptive comfort effects were observed in all regions represented in the new global database, but the neutral (comfort) temperatures in the Asian subset trended 1–2°C higher than in Western countries. Moreover, sufficient data allowed the development of an adaptive model for mixed-mode buildings that closely aligned to the naturally ventilated counterpart. We present evidence that adaptive comfort processes are relevant to the occupants of all buildings, including those that are air conditioned, as the thermal environmental exposures driving adaptation occur indoors where we spend most of our time. This suggests significant opportunity to transition air conditioning practice into the adaptive framework by programming synoptic- and seasonal-scale set-point nudging into building automation systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Largest known field study of ceiling fans sequenced with air conditioning for cooling. • Mean zone indoor temperature increased 1.9 °C in period after fan installation. • 36% total measured cooling season compressor energy savings (from 2.8 to 1.8 W/m2). • Mean ceiling fan power only 8 W, at speeds <60% maximum, fans ran 76% occupied hours. • All interviewees felt fans provided adequate cooling; most preferred automated fans. Controlled air movement is an effective strategy for maintaining occupant comfort while reducing energy consumption, since comfort at moderately warmer temperatures requires less space cooling. Modern ceiling fans provide a 2–4 °C cooling effect at power consumption comparable to LED lightbulbs (2–30 W) with gentle air speeds (0.5–1 m/s). However, very limited design guidance and performance data are available for using ceiling fans and air conditioning together, especially in commercial buildings. We present results from a 29-month field study of 99 automated ceiling fans and 12 thermostats installed in ten air-conditioned buildings in a hot/dry climate in California. Staging ceiling fans to automatically cool before, and then operate together with air conditioning enabled raising air conditioning cooling temperature setpoints in most zones, with overall positive occupant interview and survey responses. Overall measured cooling season (April– October) compressor energy savings were 36%, normalized by floor area served (41% during summer peak billing hours). Weather-normalized changes in zone energy use varied from 24% increase to 73% decrease across 13 compressors, reflecting variation in occupant schedules and other uncontrolled factors in occupied buildings. Median weather-normalized energy savings per compressor were 21%. Staging ceiling fans and air conditioning provided comfort across a wider temperature range, using less energy, than air conditioning alone. [ABSTRACT FROM AUTHOR]