Page 56 - JCAU-5-2

Journal of Chinese
Architecture and Urbanism Cooling energy-saving mechanism

Panel on Climate Change indicates that the building (Lakeridou et al., 2012). In 2007, the state council of China
construction sector has become the world’s largest energy issued the regulation that the indoor air-conditioning
consumption sector, and the building industry is an temperature in all public buildings should not be set
important contributor to the world’s energy consumption below 26°C in summer. According to the indoor design
and greenhouse gas emissions. Building construction parameters of comfortable air-conditioning stipulated
accounted for 32% of global carbon dioxide emissions in in the Code for the Design of Heating, Ventilation, and
2010. In recent decades, the proportion of global building Air-conditioning (HVAC) for Civic Buildings (GB50736-
energy consumption in total social energy consumption 2012) (Ministry of Housing and Urban-Rural, 2012), the
increased from 30% to 40% (Yu, 2017). According to the setting temperature of the long-term residence area of
US Department of Energy (DOE) energy information personnel in the cooling condition is 24°C – 28°C, and the
account, the energy consumption of existing residential temperature of the short-term residence area should be
and commercial buildings accounts for about 40% of total increased by 1°C – 2°C compared to that of the long-term
energy consumption in the US, and the proportion of residence area. ASHRAE 55-2013 (ASHREA, 2013; Office
building energy consumption in total energy consumption of Energy Efficiency & Renewable Energy, n.d.) stipulates
of the society is higher than the world’s average (Jin et al., that the temperature set-point of indoor air conditioning
2023). In all fields of Chinese society today, the building in summer should be 23°C – 27°C.
construction sector accounts for 40% of total energy Some scholars have conducted relevant research
consumption and 25% of greenhouse gas emissions combining temperature set-point and building energy
(Li et al., 2019). To reduce building energy consumption conservation. For example, Liu et al. (2022) used
and greenhouse gas emissions, scholars from all over orthogonal design and numerical simulation to explore the
the world have put forward various technical measures, influence and adaptability of different thermal properties
including adopting advanced system equipment and its of university teaching office building envelopes on energy
operation and maintenance strategies, introducing smart consumption in 12 typical cities (with different climates) in
grid systems to improve the energy efficiency of energy- China. One of the results showed that when only the winter
using end, developing new net-zero-energy buildings, or summer conditions were considered, the optimized
and carrying out energy-saving retrofits of existing envelope coefficients resulted in energy savings of 49.97
buildings (Thomas et al., 2018). However, these measures – 100% for cooling loads, and 60.6 – 100% for heating
are all from the engineering and technical point of view loads. However, when optimized for annual operating
of supplying and using energy equipment and systems conditions, annual load savings of 39.64 – 57.57% can be
and energy-consuming buildings, which require a large achieved for different climate zones. The results of this
amount of investment, are easily restricted by market rules, study can be used as a guide and data reference for energy-
and involve complex social and economic interests of saving design and retrofit of office building envelopes in
various stakeholders, thus leading to great implementation different climates. Aryal et al. (2018) pointed out that
resistance. the majority of building energy consumption comes
In recent years, with the development of people- from air-conditioning and heating systems. To maintain
oriented and passive building energy conservation a stable indoor environment for thermal comfort, the
concepts, discussions on building energy conservation temperature set-point is often set as a fixed target value,
from the perspective of occupants’ energy use behavior, ignoring the diversity of thermal comfort preferences of
such as adjusting the temperature set-point of the air- the occupants. On the one hand, the fixed set-point may
conditioning system, reducing the use of lighting and not meet the needs of thermal comfort for most people; on
equipment, and increasing the use of natural ventilation the other hand, it may waste the energy-saving potential
by opening windows, have been made (Papadopoulos et of equipment and systems. Therefore, the authors used big
al., 2019). These methods have the advantages of low cost, data analysis tools to study the relationship between the
easy operation, and considerable energy savings. Among temperature set-point and human thermal comfort, to
them, adjusting the temperature set-point is the most establish the thermal comfort model of the human body
operable for users and managers, has grand energy-saving under different climatic conditions as the basis for adjusting
potential, and has received huge attention from around the set temperature, and to study the energy-saving effect
the world. As early as 2005, the Japanese government of adjusting the set temperature in 15 cities under four
advocated that the national set-point of air-conditioners climatic conditions in the US using the DOE reference
in summer should be raised to 28°C to achieve an indirect office building model. The results showed that, compared
energy-saving effect, and then the British government with the fixed 22.5°C, the temperature set-point of the
also put forward the corresponding call due to this effect system can be adjusted according to the characteristics of

Volume 5 Issue 2 (2023) 2 https://doi.org/10.36922/jcau.0877