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.

Impact of climate change on thermal comfort and energy performance in offices - a parametric study

This paper investigates the impact of climate change on comfort and energy performance in offices in relation to the influence of building design and occupants. It focuses on a typical cellular office room in the context of Athens, Greece, as input for a parametric study using the building simulation software EnergyPlus. Three different building design variations are combined with two different occupant scenarios and 4 different weather data sets for IPCC climate change scenario A2.

For naturally ventilated buildings adaptive thermal comfort is evaluated according to ASHRAE Standard 55 and EN 15251. For mixed mode context evaluation is focused on greenhouse gas emissions and peak heating / cooling loads. Results indicate significant impact of the climate change on thermal comfort, and deviations between both comfort models. Comparing climate change, building design and occupant scenarios indicates that building design is the predominant influence on thermal comfort, whereas occupants are the predominant influence on greenhouse gas emissions.

Designing for 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 heat transfer behaviour of the glazing. In this study, several glazing systems were designed using the software tools VISION 3 (University of Waterloo 1992) and WINDOW-6 (Lawrence Berkeley National Laboratory 2011), with a view to improving thermal environment of occupants near the glazed wall of a commercial office. The systems were fabricated and experimentally tested to validate the software modelling results. Subsequently, the glazing systems were retro-fitted to the office and tested in situ for a summer month. Results of this testing, in the form of Fangers’ predicted mean vote (PMV) and the predicted percentage dissatisfied (PPD), are presented, and some options for improving the thermal environment in this near-façade zone are discussed.

Measurement and solutions to thermal comfort, CO2 and ventilation rates in schools

An Australian research facility, conducted a study on several different school classrooms in regards to their thermal comfort, CO2 levels, air temperature stratification and ventilation rates in a selection of Victorian (Melbourne, Australia) schools during a winter season. A brief literature review reveals similar IAQ problems elsewhere (outside Australia) and suggests several HVAC concepts that provide potential solutions. Our intention is to highlight particular IAQ discrepancies in existing school classroom design resulting from these case study measurements, suggesting construction and mechanical operational conditioning improvements.In particular this research confirms the urgency and necessity of addressing IAQ problems in schools, world wide. Our results of the Australian school classroom measurements are similar to other parts of the world, indicating that CO2 levels, ventilation rates and air temperatures are non-compliant with the standards.