On the influence of building design, occupants and heat waves on comfort and greenhouse gas emissions in naturally ventilated offices. A study based on the EN 15251 adaptive thermal comfort model in Athens, Greece

According to the Intergovernmental Panel on Climate Change the buildings sector has the largest mitigation potential for CO2 emissions. Especially in office buildings, where internal heat loads and a relatively high occupant density occur at the same time with solar heat gains, overheating has become a common problem. In Europe the adaptive thermal comfort model according to EN 15251 provides a method to evaluate thermal comfort in naturally ventilated buildings. However, especially in the context of the climate change and the occurrence of heat waves within the last decade, the question arises, how thermal comfort can be maintained without additional cooling, especially in warm climates. In this paper a parametric study for a typical cellular naturally ventilated office room has been conducted, using the building simulation software EnergyPlus. It is based on the Mediterranean climate of Athens, Greece. Adaptive thermal comfort is evaluated according to EN 15251. Variations refer to different building design priorities, and they consider the variability of occupant behaviour and internal heat loads by using an ideal and worst case scenario. The influence of heat waves is considered by comparing measured temperatures for an average and an exceptionally hot year within the last decade. Since the use of building controls for shading affects thermal as well as visual comfort, daylighting and view are evaluated as well. Conclusions are drawn regarding the influence and interaction of building design, occupants and heat waves on comfort and greenhouse gas emissions in naturally ventilated offices, and related optimisation potential.

Context dependency of comfort and energy performance in mixed mode offices

This article investigates the context dependency of comfort and energy performance in mixed-mode offices in the climate of Athens, Greece. It is based on a parametric study using the simulation software EnergyPlus. Context refers to different building design priorities on the real estate market (prestige, low cost and green), occupant behaviour scenarios (ideal and worst case) and cooling strategies (fixed and adaptive set points). Results are evaluated according to energy consumption and related greenhouse gas emissions, daylight autonomy, view and percentage of working time when heating and cooling are operating. The results indicate that a holistic approach to comfort and energy performance evaluation focused on the specific context of a building and its occupants is necessary to develop appropriate optimization strategies. In early design stages, such specific information is not yet available and ideal/worst-case scenarios can indicate the magnitude of influence of occupants compared to building design.

The effect of planning design on thermal comfort in outdoor spaces

Urban outdoor spaces are considered essential elements of cities, where the greatest amount of human contact and interaction takes place. That is the reason why there is increasing public interest in the quality of open urban spaces as they can contribute to the quality of life within cities, or contrarily increase isolation and social exclusion. There are a lot of factors influencing the success of the outdoor spaces; one of the principal factors is the microclimatic comfort. In the hot areas, the outdoor thermal comfort conditions during the daytime are often far above acceptable comfort standards due to intense solar radiation and high solar elevations. The variation of the urban spaces' configuration can generate significant modifications of the microclimatic parameters. Design decisions such as street and sidewalk widths, shading structures, materials, landscaping, building heights, and inducing air flow have a significant impact on the pedestrian thermal comfort and subsequently on the use of the urban environment. Although it has been established that the vegetation elements should be considered as one of the main tools that can be used in improving the thermal comfort in outdoor spaces, the integration of the climate dimension in the planting design process in urban spaces is lacking because of insufficient interdisciplinary work between urban climatology, urban design and landscape architecture. The primary aim of this research is to study the influence of some of the design decision for the plantation elements in outdoor spaces on the thermal comfort of its users. This will provide landscape designers and decision makers with the appropriate tools for effectively assessing the development of urban environment while considering the microclimate of outdoor spaces. A special emphasis is put on summertime conditions in Egypt. Findings of this research will contribute to sustainable urban design of outdoor spaces.

Too close for comfort : a fishway exit and a hydro-power station inlet

A major environmental issue for hydro-electric power generation is passage of fish through turbines, or entrainment onto trash racks. At Yarrawonga Weir, on the upper Murray River in south-eastern Australia, the positioning of a fish lock resulted in the potential for upstream migrating fish to be swept back into the adjacent power station by cross flows. In 2004, a 4.5-m long steel extension flume was attached to the exit to alleviate this problem. To determine the fate of native fish after exiting the extension flume, 72 individuals (305–1015 mm long) were implanted with radio-transmitters and released into the fish lock exit channel. In 2004 (power station inflows 10 300 ML day^–1), the majority of fish exited successfully (44 of 45) and only a single fish (2%) was entrained into the power station. In 2005 (power station inflows 12 000 ML day^–1), fish again exited successfully (26 of 27) but with a higher proportion entrained (5 of 27; 18%). This reduced success appeared to be related to strong transverse flows with high water velocities adjacent to the fish lock exit. The efficiency of fish passage at this site might be improved by altering water management strategies, integrating engineering and fish biology, and through field-testing of proposed solutions

Neuromuscular adaptations to training, injury and passive interventions: implications for running economy

Performance in endurance sports such as running, cycling and triathlon has long been investigated from a physiological perspective. A strong relationship between running economy and distance running performance is well established in the literature. From this established base, improvements in running economy have traditionally been achieved through endurance training. More recently, research has demonstrated short-term resistance and plyometric training has resulted in enhanced running economy. This improvement in running economy has been hypothesized to be a result of enhanced neuromuscular characteristics such as improved muscle power development and more efficient use of stored elastic energy during running. Changes in indirect measures of neuromuscular control (i.e. stance phase contact times, maximal forward jumps) have been used to support this hypothesis. These results suggest that neuromuscular adaptations in response to training (i.e. neuromuscular learning effects) are an important contributor to enhancements in running economy. However, there is no direct evidence to suggest that these adaptations translate into more efficient muscle recruitment patterns during running. Optimization of training and run performance may be facilitated through direct investigation of muscle recruitment patterns before and after training interventions.

There is emerging evidence that demonstrates neuromuscular adaptations during running and cycling vary with training status. Highly trained runners and cyclists display more refined patterns of muscle recruitment than their novice counterparts. In contrast, interference with motor learning and neuromuscular adaptation may occur as a result of ongoing multidiscipline training (e.g. triathlon). In the sport of triathlon, impairments in running economy are frequently observed after cycling. This impairment is related mainly to physiological stress, but an alteration in lower limb muscle coordination during running after cycling has also been observed. Muscle activity during running after cycling has yet to be fully investigated, and to date, the effect of alterations in muscle coordination on running economy is largely unknown. Stretching, which is another mode of training, may induce acute neuromuscular effects but does not appear to alter running economy.

There are also factors other than training structure that may influence running economy and neuromuscular adaptations. For example, passive interventions such as shoes and in-shoe orthoses, as well as the presence of musculoskeletal injury, may be considered important modulators of neuromuscular control and run performance. Alterations in muscle activity and running economy have been reported with different shoes and in-shoe orthoses; however, these changes appear to be subject-specific and nonsystematic. Musculoskeletal injury has been associated with modifications in lower limb neuromuscular control, which may persist well after an athlete has returned to activity. The influence of changes in neuromuscular control as a result of injury on running economy has yet to be examined thoroughly, and should be considered in future experimental design and training analysis.

Assessment of thermal comfort near a glazed exterior wall

In many highly glazed buildings, the thermal comfort of the occupants will tend to be related to the incoming solar energy and the solar heat gain coefficient of the glazing. Many real buildings tend to be deep relative their height and therefore, areas close to the facade receive a much greater amount of the incoming energy than those farther from it. In turn, this imbalance leads to occupants near the facade experiencing a high dissatisfaction with their thermal environment (near-facade zone). This study experimentally examines the thermal environment of occupants near the facade of a glazed building wall. It presents results for Fangers’ predicted mean vote (PMV) and the predicted percentage dissatisfied (PPD) and explores some options for improving the thermal environment in this near-facade zone.

Climate change sensitivity of comfort and energy performance criteria for offices

The climate change scenarios of the Intergovernmental Panel on Climate Change (IPCC) predict a significant increase in temperatures over the next decades. Architecture and building occupants have to respond to this change, but little information is currently available in how far the predicted changes are likely to affect comfort and energy performance in buildings. This study therefore investigates the climate change sensitivity of the following parameters: adaptive thermal comfort according to Ashrae Standard 55 and EN 15251, energy consumption, heating and cooling loads, and length of heating and cooling periods. The study is based on parametric simulations of typical office room configurations in the context of Athens, Greece. They refer to different building design priorities and account for different occupant behaviour by using an ideal and worst case scenario. To evaluate the impact of the climate change, simulations are compared based on a common standard weather data set for Athens, and a generated climate change data set for the IPCC A2 scenario. The results show a significant impact of the climate change on all investigated parameters. They also indicate that in this context the optimisation of comfort and energy performance is likely to be related to finding the best possible balance between building (design) and occupant behaviour and other contextual influences, rather than a straightforward optimisation of separated single parameters.

Comparison of the EN 15251 and Ashrae Standard 55 adaptive thermal comfort models in the context of a Mediterranean climate

Strong heat waves in the past decade and resulting legal cases which gave full responsibility for indoor thermal comfort to building professionals lead to an increased uncertainty how to maintain thermal comfort in offices without the use of a cooling system. Adaptive thermal comfort standards such as EN 15251 and Ashrae Standard 55 provide methodologies to evaluate comfort in naturally ventilated spaces. Based on a parametric study for a typical cellular office in the context of Athens, Greece, and using the building simulation software EnergyPlus, this study investigates the potentials for the applicability of natural ventilation in a Mediterranean climate. The Ashrae Standard 55 and EN 15251 adaptive thermal comfort models are compared in this context, and conclusions are drawn how the use of natural ventilation based on adaptive models can be further encourgaged.

Effect of gender on thermal comfort in multicultural public places

The city and the urban environment became extremely important in the daily lives of the increasing number of urban populations across the world. Urban research acknowledges that planning urban places should be responsive to the diversity of population. The aim of this paper is to analyse the results of thermal comfort study in the outdoor urban places. The location has been monitored regarding standard comfort variables: air temperature, humidity, wind speed, and globe temperature. The quantitative assessment of comfort conditions was combined with a questionnaire of pedestrians’ thermal comfort perception. In this paper, the analysis of observed thermal sensation with regard to gender and cultural background concerning the sensitivity of different groups to heat and cold is presented.

Thermal comfort adaptation in outdoor places

The level of international migration has been growing in the last decades creating a plurality of cultures and inspiring a multicultural nature in global cities (O'Byrne, 1997; Short and Kim, 1999; Hawkins, 2006). This created new challenges in urban planning or the management of the coexistence of different people that are having different characteristics shaping their unique identity and needs in shared places. Being the urban stages where the social interactions happen, public places are considered important parts of cities (Thompson, 2002; Varna, 2009). These places can contribute to enhance the quality of life within cities, or contrarily increase isolation and social exclusion (Lo et al.; 2003). As agreed by researchers the users’ state of comfort gives a good indication for how successful is the public outdoor places (Rosheidat et al.; 2008; Kwong et al.; 2009; Aljawabra and Nikolopoulou, 2010). In order to create a successful open space usable by all members of a community, urban designers need to satisfy their thermal comfort needs in its wider meaning according to a variety of users (Knez and Thorsson, 2006; Thorsson et al.; 2007). While assessing the thermal comfort, in addition to the strong influence of the microclimatic parameters, the term thermal adaptation seems to becoming increasingly important. The thermal comfort adaption is then a considerable issue in design guidelines of outdoor environments (Nikolopoulou and Steemers, 2003). The main aim of the research is to examine the influence of thermal adaptation and environmental attitude on participants’ thermal requirements in outdoor public places. It focuses on understanding the effect of adaptation on the thermal comfort perception of immigrants. The research methodology of the research is provided through quantitative analysis of a case study. The findings of thermal comfort investigations could be applied into improving the quality of urban areas in order to increase the outdoor activities of citizens and use of outdoor places.

Diversity and thermal comfort in outdoor places

Sustainable cities should be livable cities where people from different backgrounds and with different aspirations can meet and interact with each other. Public places being the urban stages where the social interactions happen are considered important parts of cities (Thompson, 2002; Varna, 2009). They can contribute to enhance the quality of life within cities, or contrarily increase isolation and social exclusion (Lo et al., 2003). As a consequence of globalization and the development of global cities, the level of international migration has been growing in the last decades creating a plurality of different cultures in global cities and inspiring in such cities a multicultural nature (O'Byrne, 1997; Short and Kim, 1999; Hawkins, 2006). This created new challenges in urban planning or the management of the coexistence of different people that are having different characteristics that shape their unique identity and needs in the shared spaces (Sandercock, 2004). Ideally, in order to invite a diversity of users, urban outdoor places should provide significant functional and physical qualities, and accessibility to them, which induce the fulfillment of physiological, psychological and social needs (Carr et al., 1992; Jacobs, 1993; Sandholz, 2007). Users’ state of comfort as stated by researchers gives a good indication for how successful is the public outdoor places (Rosheidat et al., 2008; Kwong et al., 2009; Aljawabra and Nikolopoulou, 2010). In order to create a successful open space usable by all members of a community, urban designers need to satisfy their comfort needs in its wider meaning according to a variety of different ages, genders and cultural backgrounds (Knez and Thorsson, 2006; Thorsson et al., 2007). The main aim of the research is to examine the influence of culture and environmental attitude on participants’ thermal requirements in outdoor public places. The paper explores the variables that constitute a successful multicultural design, issues of cultural complexity, and the measuring comfort in specific outdoor public place. Qualitative analysis of a case study provides the main research methodology of the research. The conclusion will provide a set of criteria that guide future design and development of a successful shared outdoor public places.

The effect of humidity and temperature on Wool Comfort Meter assessment of single jersey wool fabrics

The Wool ComfortMeter provides an objective measurement of the fabric-evoked prickle discomfort rating provided by wearers. This work aimed to quantify the sensitivity of the Wool ComfortMeter over a range of different temperature and humidity conditions to determine the recommended test conditions for its operation. The design was: three temperatures (notionally 20, 25 and 30°C) at three relative humidities (RHs, notionally 50, 65 and 80%) each with two replicates, using six different wool single jersey knits (mean fibre diameter 19.5–27.0 µm). As it was difficult to achieve exactly some of the extreme combinations of temperature and RH, some combinations were repeated, providing a total of 23 different assessment conditions. Data were analysed using restricted maximum likelihood mixed model analysis. The best fixed model included RH, RH2, temperature and the interaction of temperature and RH, accounting for 95% of the variation in Wool ComfortMeter readings. Wool ComfortMeter values were almost constant at 55–60% RH. Generally, the Wool ComfortMeter value reduced with increasing RH > 60% at temperatures of 25°C and 28.5°C as the regain of the fabric increased. However, at 20°C little change was detected as RH was increased from 50 to 80% as there were only small changes in fabric regain. The observed effects were in a good agreement with existing knowledge on the effect of regain on the mechanical properties of wool fibre. Wool ComfortMeter is best operated under standard conditions for textile testing of 65% RH and 20°C.

Comfort and adaptation to silicone hydrogel lenses for daily wear

Objectives. To investigate initial comfort and adaptation of currently successful low oxygen transmissibility soft lens wearers refitted with silicone hydrogel (SH) lenses for daily wear.

Methods. Fifty-five subjects were enrolled in a subject-masked 5-month clinical trial in which they wore 5 SH lenses in a randomized, crossover design. Comfort, burning, and dryness were rated on scales of 0 to 100 immediately on insertion and the time for lens settling was recorded. Symptoms were then rated at various times, using BlackBerry wireless communication devices (Research in Motion, Waterloo, Canada), during the day for 2 cycles of 2 weeks wear for each lens type.

Results. Comfort immediately on insertion varied between lens types (P=0.002). All lens types were reported by the subjects to have settled within 30 to 45 sec of insertion (P=0.14) and settled comfort was greater than comfort immediately on insertion (P<0.001). Comfort within the first hour of wear also varied between lens types (P=0.02). Comfort during the day decreased significantly for all lenses (P=0.001), but there was no difference between lenses (P=0.19) and no effect of lens age (P=0.15). The wearing times were greater with the SH lenses than the habitual lenses worn before study commencement (P=0.001). Overall performance of the lenses after 4 weeks was high, with no difference between lenses (P=0.45).

Conclusions. Initial comfort and adaptation to all SH lenses were good and no differences in the overall ratings were found between the 5 SH lenses investigated. Decreased comfort was noted later in the day with all lens types, but longer wearing times were reported with the SH lenses than previous hydroxyethyl methacrylate-based lenses.