Hom B. Rijal

Development of an adaptive window-opening algorithm to predict the thermal comfort, energy use and overheating in buildings

This investigation of the window-opening data from extensive field surveys in UK office buildings demonstrates: (1) how people control the indoor environment by opening windows; (2) the cooling potential of opening windows; and (3) the use of an ‘adaptive algorithm’ for predicting window-opening behaviour for thermal simulation in ESP-r. It was found that when the window was open the mean indoor and outdoor temperatures were higher than when closed, but it was shown that nonetheless there was a useful cooling effect from opening a window. The adaptive algorithm for window-opening behaviour was then used in thermal simulation studies for some typical office designs. The thermal simulation results were in general agreement with the findings of the field surveys. The adaptive algorithm is shown to provide insights not available using non adaptive simulation methods and can assist in achieving more comfortable, lower energy buildings while avoiding overheating.

Investigation of comfort temperature, adaptive model and the window-opening behaviour in Japanese houses

This study described in this paper was undertaken to investigate comfort temperatures and related behaviours in Japanese homes. In it temperatures were measured in the living rooms and a thermal comfort survey of residents and related window-opening behavioural survey was completed over a full year in the Gifu region of Japan. The residents were found to be highly satisfied with the thermal environment of their houses. Significant seasonal differences were found in their comfort temperatures. The results showed that comfort temperature changes varied with changes in both the indoor and outdoor climate. The strength of the relationship between indoor and outdoor temperatures justified the adoption of the adaptive model for both prediction and design of control strategies for the provision of indoor comfort. The window-opening behaviours were shown to be related to both the indoor or outdoor air temperatures. The deadband was narrower and constraints on the window opening in the houses investigated were both considerably lower than previously found in office building studies. The adaptive model is highly supported by this study of occupant perceptions and window-opening behaviour.

Considering the impact of situation-specific motivations and constraints in the design of naturally ventilated and hybrid buildings

A simple logical model of the interaction between a building and its occupants is presented based on the principle that if free to do so, people will adjust their clothing or available building controls with the aim of achieving or restoring comfort and reducing discomfort. These adjustments are related to building design in two ways: first, the freedom to adjust depends on the availability and ease of use of control options; second, the use of controls affects building comfort and energy performance. The values of constraints are quantified for a range of existing buildings in Europe and Pakistan. The integration of the model within a design flow is proposed and the impact of different levels of constraints demonstrated. It is proposed that to minimize energy use and maximize comfort in naturally ventilated and hybrid buildings the designer should take the following steps: (i) provide unconstrained low-energy adaptive control options where possible, (ii) avoid problems with indoor air quality which provide motivations for excessive ventilation rates, (iii) incorporate situation-specific adaptive behaviour of occupants in design simulations, (iv) analyse the robustness of designs against variations in patterns of use and climate and (v) incorporate appropriate comfort standards into the operational building controls.

Towards an adaptive model for thermal comfort in Japanese offices

ABSTRACT This study investigates the seasonal adaptation to temperature that occurs in Japanese offices, with a view to suggesting an adaptive model for them. Temperatures were measured in 11 office buildings and thermal comfort transverse surveys of occupants were conducted for over a year in the Tokyo and Yokohama areas of Japan. A total of 4660 samples were collected from about 1350 people. The occupants were found to be highly satisfied with the thermal environment in their offices. Even though the Japanese government recommends the indoor temperature setting of 28°C for cooling and 20°C for heating, the comfort globe temperature was found to be 2.6°C lower in cooling mode and 4.3°C higher in heating mode, in line with actual indoor temperatures. The monthly and seasonal variation in the comfort temperature was found to be significantly lower than those in dwellings. The comfort temperature is related primarily to the indoor temperature, but an adaptive relationship can be derived to estimate the indoor comfort temperature from the prevailing outdoor temperature for similar office buildings.

Drivers and barriers to occupant adaptation in offices in India

Occupant window-opening behaviour in Indian offices is a nascent field. This paper relies on the thermal comfort field study data from 28 Indian offices in Hyderabad and Chennai. Occupants in naturally ventilated buildings used the windows and doors adaptively as the seasons changed and the temperature varied. We found that 50% of the windows would be opened at an indoor air temperature of 30 °C, using logistic regression. We noted some non-thermal factors possibly affecting the adaptive operation of controls as well, including: design and construction, operation and maintenance, environmental, sociocultural, attitudinal and behavioural factors. A windows potential for modifying the comfort temperature hinges on the effective handling of these hurdles. We further categorized the barriers into those in the occupants realm and beyond. Each category is further identified with the extent to which the barrier interferes with the control as an adaptive opportunity.

Field survey of the thermal comfort, quality of sleep and typical occupant behaviour in the bedrooms of Japanese houses during the hot and humid season

In order to investigate the thermal comfort, quality of sleep and behaviour of the occupants of Japanese bedrooms in the hot and humid season, we have measured the air temperature and relative humidity in the 26 bedrooms of 10 houses, and conducted a thermal comfort, depth of sleep and occupant behaviour survey with 31 residents, obtaining 1176 votes. The mean indoor air temperature in the rooms during the survey period was 26.3–27.9°C. The residents sleep in the bedrooms, where the indoor air temperature is high. The mean comfort temperature is 26.4–27.1°C. The thermal comfort of residents is high and the depth of sleep is normal for the given thermal environment. The results showed that residents are thermally satisfied and slept well in the bedrooms using various thermal adjustments, such as cooling, fans, windows and clothing insulation.

Thermal Adaptation Outdoors and the Effect of Wind on Thermal Comfort

People use outdoor spaces for various reasons. It is important to create the optimum wind environment to achieve adaptive thermal comfort in a hot and humid climate. To clarify thermal adaptation in the outdoor environment, thermal comfort surveys are reviewed and compared. Semi-outdoor spaces, which have a similar function to the outdoor environment, are also included in the analysis. To clarify the effect of the wind on thermal comfort, indoor thermal comfort surveys are reviewed. The results show that the outdoor comfort temperature is highly correlated with the monthly mean outdoor temperature, indicating the existence of regional and seasonal differences in comfort temperature. The proposed adaptive model can be used to predict the outdoor comfort temperature. Increased wind velocity raises the comfort temperature especially in hot and humid climates.

Window Opening Behaviour in Japanese Dwellings

We investigated window opening behaviour and thermal environment over a period of 4 years in the living rooms and bedrooms of dwellings in the Kanto region of Japan. We collected 36,144 data samples from 243 residents of 120 dwellings. The proportion of ‘open window’ in the free-running mode is significantly higher than that in the cooling and heating modes. The window opening behaviours were shown to be related to both the indoor or outdoor air temperatures. Window opening behaviour as predicted by logistic regression analysis is in agreement with the measured data. The deadband was narrower, and constraints on the window opening in the investigated dwellings were considerably smaller than had previously been found in studies of office buildings. An adaptive algorithm is developed that can be applied to predict window opening in Japanese dwellings.

Development of a window opening algorithm based on adaptive thermal comfort to predict occupant behavior in Japanese dwellings

Window opening behavior and thermal comfort were monitored in relation to the thermal environment over a 4 year period in the living rooms and the bedrooms of dwellings in the Kanto region of Japan. 36 144 sets of physical and subjective data were collected from 243 residents of 120 dwellings. This paper explores relationships between the different variables in the data. The likelihood of windows being open depended on the three modes of operation of the dwelling, free running (FR), heating (HT) or cooling (CL). In the FR mode, the likelihood was much higher than in either the CL or the HT modes. The likelihood that a window is open correlated well with both indoor temperature and outdoor air temperature in the FR Mode. The indoor comfort temperature correlated well with the running mean of the outdoor temperature. Window opening behavior as predicted by logistic regression analysis is in agreement with the measured data. The deadband of window opening was narrower, and the constraint on window opening was smaller than had previously been found in studies in office buildings. Equations are given to quantify these relations and to enable window opening and comfort temperature to be predicted from outdoor temperature.

Designing for comfort at high temperatures

It would be foolish to ignore the potentially disastrous impacts of designing buildings that overheat in a warming world. We know that hot buildings not only can make people uncomfortable, unhappy and unproductive but they can also kill people. During the extreme heatwave summer of 2003 over 70,000 people across Europe died, many of them elderly and many in their own homes. Robine et al. (2008) who compiled these 2003 figures pointed out that global warming now constitutes an emerging transnational health threat, particularly for ageing populations, that needs addressing at many levels (Roaf, Crichton, and Nicol 2009). Climate predictions indicate that by 2050 the extreme summer of 2003 may occur every second year and by 2070 it may be classified as a cool summer (Nakicenovic and Swart 2010). Maivel, Kurnitski and Kalamees, in their paper, present the results of a field survey in Estonian apartment buildings and demonstrate that even in northern European latitudes buildings, and noticeably more often modern ones, are overheating already. They propose that even in Nordic countries, the recommended passive measures to tackle overheating may need to be supplemented with active cooling systems to meet the minimum requirements for summer thermal comfort defined by regulations. The question thus arises as to whether the regulations are ‘Fit for Purpose’ in a warming world. The fact that ‘modern’ design trends and construction techniques have led to a greater tendency for nontraditional buildings to overheat has been known for at least 50 years. In the UK in the 1960s, a study by Loudon and Danter (1965) at the Building Research Establishment showed that post-World War II architecture was changing rapidly as lighter weight buildings with more glass replaced the traditional modes of construction. In pre-war offices the window areas averaged around 20% of the floor area and 85% of surveyed occupants wanted more sunshine in their offices, and only 9% were concerned that it should not be too hot. By 1961 this survey in 21 postwar offices shows that as many as 40% of the occupants