A review of factors affecting occupant comfort in multi-unit residential buildings

Buildings consume energy for different purposes. One core function is to provide healthy and comfortable living conditions for the humans that inhabit these buildings. The associated energy use is significant: taken together, buildings are responsible for roughly 40% of the world’s total annual energy consumption. This large percentage makes the built environment an important target for researchers, policy makers, innovators and others who aim to decrease energy consumption and the associated emissions of Greenhouse Gases (GHG). Unfortunately, the significant body of research on energy efficient buildings conducted since the 1970s has had only a limited impact on the overall energy use of the sector, and this remains a serious concern. The energy use of buildings shows a strong correlation with the activities of the building occupants. A key factor that makes it hard to curb building energy use is a lack of understanding of building occupant behaviour. This paper reviews research on building occupant behaviour in two stages. The first stage reviews important issues, milestones, methodologies used, building types analysed and progress achieved related to the topic, as reported in the most frequently cited papers. The second stage focuses on recent work in the area and investigates ‘state of the art’ developments in terms of questions asked and solutions proposed. The aim is to identify problems and knowledge gaps in the field for future projection. Recent research on the topic is analysed, taking account of methodologies, building types, locations, keywords, data sampling and survey size. Based on a critical analysis of the literature, the following outcomes can be reported: research on building occupant behaviour relies strongly on quantitative methods, but studies are mostly located in the northern hemisphere and in developed and high-income countries. The dominant research topics associated with occupant behaviour are energy demand and thermal comfort, followed by retrofit and renovation. Most research focuses on technical aspects rather than socio-economic issues. Current research is mostly limited to studies of single buildings and typically lacks data-gathering standards, which makes it hard to conduct cross cultural data comparisons. Most research concentrates on individual topics, such as window, door and blind adjustments, effects of Heating Ventilating Air Condition (HVAC) systems etc. and does not provide a wider, holistic view that can be linked to social and economic factors.

The interaction between humans and buildings for energy efficiency: A critical review

Optimizing energy efficiency and thermal comfort in building green retrofit

In order to quantify the seasonal differences in the comfort temperature and to develop a domestic adaptive model for highly insulated Japanese dwellings, thermal measurements and a thermal comfort...

Development of an adaptive thermal comfort model for energy-saving building design in Japan

Methods used in social sciences that suit energy research: A literature review on qualitative methods to assess the human dimension of energy use in buildings

We conducted a series of survey on occupants’ behaviors for adaptive thermal comfort together with indoor air temperature measurement in a condominium equipped with Home Energy Management System (HEMS), from November 2015 to October 2016, in which 17,026 votes were collected. The data was categorized into Free Running (FR), Cooling (CL) and Heating (HT) mode and were analyzed thoroughly. The results showed that the indoor air temperature was highly correlated with outdoor air temperature in FR mode. In CL mode, the mean indoor air temperature was 27.3 °C, which was close to the recommended air temperature for summer in Japan equal to 28 °C. In HT mode it was found that indoor air temperature was maintained around 20 °C. Similar indoor air temperature was also observed in FR mode during winter. The occupants’ thermal sensation votes were most likely to be neutral. The mean clothing insulation was 0.43 clo in summer and 0.89 clo in winter. The occupants’ behaviors in this condominium for clothing insulation adjustment were found to be quite similar to those in detached houses found in previous studies. The occupants seemed adapting to the indoor thermal environment by window-opening behaviors to adjust thermal comfort during summer. The use of fan was found to increase as the indoor air temperature increased. The occupants were found to take these passive means along with the use of air conditioning unit for cooling. Mechanical heating was used only for a limited period for the condition of outdoor air temperature being low.

An in-situ study on occupants’ behaviors for adaptive thermal comfort in a Japanese HEMS condominium

A home energy management system (HEMS) shows the energy used indoors so that the energy waste can be easily identified and reduced. Thermal comfort is related to the trend of energy use in buildings. We conducted a survey in a condominium equipped with a HEMS to determine the indoor thermal environment and various behaviors of the occupants taken for thermal comfort adjustment. The results showed that there is a large variation of indoor air temperatures according to season, floor and flat. We categorized families into two groups, one with higher and the other with lower average indoor temperatures. The indoor air temperature of the higher temperature group in summer was found to be higher than the recommended indoor temperature during the summer season in Japan. The higher temperature group tended to adopt behaviors, such as window opening and using a fan more often, than the lower temperature group. Due to the moderately high insulating levels in the building surveyed, the indoor air temperature of both groups was not low in winter. Heating was used less and irregular. The overall results indicate that the groups of families behaved differently to adjust the indoor thermal environment even though they were equipped with the same HEMS system.

https://www.mdpi.com/2075-5309/9/1/4/pdf/1

An Investigation of the Behavioral Characteristics of Higher- and Lower-Temperature Group Families in a Condominium Equipped with a HEMS System

A residential cogeneration system (CGS) is highlighted because of its efficient energy usage on both the supplier and consumer sides. It generates electricity and heat simultaneously; however, there is insufficient information on the efficiency according to the condition of usage. In this study, we analysed the performance data measured by the home energy management system (HEMS) and the lifestyle data of residents in a condominium of 356 flats where fuel cell CGS was installed in each flat. The electricity generated by CGS contributed to an approximately 12% reduction in primary energy consumption and CO2 emission, and the rate of generation by the CGS in the electric power demand (i.e., contribution rate) was approximately 38%. The electricity generation was mainly affected by the use of electricity up to 4 MWh/household/year. Gas or water use also impacted electric power generation, with water use as the primary factor affecting the contribution rate. Electric power generation changes monthly, mainly based on the water temperature. From these results, we confirmed that a CGS has substantial potential to reduce energy consumption and CO2 emission in condominiums. Thus, it is recommended for installation of fuel cell CGS in existing and new buildings to contribute to the energy-saving target of the Japanese Government in the residential sector.

Kazui Yoshida

Papers

Development of an adaptive thermal comfort model for energy-saving building design in Japan

An in-situ study on occupants’ behaviors for adaptive thermal comfort in a Japanese HEMS condominium

An Investigation of the Behavioral Characteristics of Higher- and Lower-Temperature Group Families in a Condominium Equipped with a HEMS System

Energy-Saving and CO2-Emissions-Reduction Potential of a Fuel Cell Cogeneration System for Condominiums Based on a Field Survey

Feasibility Study on the Use of HEMS for Thermal Comfort and Energy Saving in Japanese Residential Buildings