1. Introduction
For the design of ‘nearly zero-energy’ buildings (NZEB) [
1], there are two aspects needing to be considered, IEQ (Indoor Environmental Quality) and Energy saving/efficiency. First, at the international level (EU, USA) the new legislations claim that NZEB goals have to be reached in the presence of acceptable IEQ levels for occupants. This is especially for Health Facilities (hospital buildings) where IEQ requirements have to be calibrated by thinking about two different groups of people: on one hand the patients, and the medical/paramedic staff. Therefore, there are many literatures were conducted to investigate IEQ in hospital buildings [
2,
3,
4,
5,
6,
7,
8,
9,
10]. Among them, Fanger’s studies are very important in the field of indoor environment quality, which have inspired (and still inspire) professional design engineers and academic researchers on human thermal comfort and indoor air quality [
11]. Secondly, under the premise of considering IEQ, hospital energy saving research is also a very key issue.
As we know, building energy consumption has kept rising during the past few decades, and the proportion of building sections rose form 10% in 1980 to more than 30% now [
12,
13]. Recently, China has become the largest energy consumer in the world [
14]. In particular, hospital’s energy use is more than twice as much as other general public buildings. The higher energy use in hospital buildings is due to the high space heating, cooling and ventilation loads, continuous operation for the majority of facilities, and high number of medical equipment [
15]. Therefore, hospitals should be the most important in implementing energy saving and environmentally sustainable development [
16].
First, it is significant to conduct a national statistical investigation of hospital energy consumption. In recent years, there are many related studies being developed. For example, in 1999 Ahmed H.S [
17] suggested that the economic and technological considerations must be observed in the design and construction of hospitals in the low-income regions of developing countries. In 2007 in UK [
15], in order to reduce primary energy consumption by 15% during this decade, for all existing buildings the healthcare target is to improve the total energy consumption to a level of 445 kWh/m
2 and 550 kWh/m
2 for good practice and typical practice, respectively. For Asia [
18], Japanese researchers conducted a sensitivity analysis in structure optimization of energy supply systems for a hospital in 2007.
It can be concluded that there are not many comprehensive investigations of energy consumption performance of hospitals. Especially, in China, there is hardly any comprehensive energy investigation data of hospitals with different levels in all over climatic zones. This study, therefore, was motivated to conduct a comprehensive investigation to fill this gap for the first time. The purpose is to clarify the status of energy consumption, to identify and to illustrate the weak links for hospital buildings’ energy efficiency improvement.
Secondly, it is also necessary to give a reasonable evaluation of the energy consumption of hospital buildings based on this investigation. There are various rating systems that can be used on assessment in operation and management of energy systems in hospitals. BREEAM is the earliest rating system of green buildings and was created in U.K in 1990 [
19,
20]. Among the BREEAM products, BREEAM Healthcare version was developed in 2008 for green hospital buildings [
21]. LEED is another commonly used green building rating system, which was launched by U.S. Green Building Council in 1998 [
22,
23,
24]. Among the LEED products family, LEED for Healthcare was released by USGBC in 2011. What’s more, Green Guide for Health Care (GGHC) is created by Steering Committee from U.S. healthcare industry [
25,
26]. Rating systems in these developed countries have set a good example for other countries.
However, different countries have different characteristics of energy consumption and influence mechanisms, so the rating methods must suit the actual conditions of their own countries. Hence, in 2006, China issued Evaluation Standard for Green Building (ESGB), which is the first multi-objective and multi-level comprehensive evaluation standard of green building “environment performance grade” in China [
27,
28,
29]. However, it is vacant in rating systems of hospitals in China. In this instance, a rating system of energy consumption in the hospital building sector needs to be established in China.
Therefore, in this study, the comprehensive energy investigation of hospitals in China was undertaken to investigate the status of energy consumption. Then a new evaluation system of energy consumption in operation and management for hospitals was established, and which can identify the weak links in energy efficiency of energy supply system of a hospital. The results obtained by this paper provide owners and operators of hospitals in China to enhance the efficient of energy-savings.
4. Evaluation of Building Energy-Saving
According to the investigation above, it can be concluded that there is a specific trend of energy consumption of hospital buildings, and operation and management is very important to hospital building, while, at present, there is no national standard for the operation and management of hospital buildings in China. Due to the difference of national conditions, there are obvious differences in relevant codes and standards, so foreign standards cannot be blindly copied. Moreover, the existing evaluation indexes “green hospital building evaluation standard” in China has some shortcomings in operation evaluation. Therefore, this paper attempts to establish an evaluation system suitable for China’s national conditions and targeted at the operation and management of hospital buildings.
Combined with investigation results, this paper proposed a novel evaluation system of building energy-saving for hospitals in China. The establishment of the evaluation system is based on a careful analysis of LEED HC in US, GGHC operations and Assessment Standard for Healthcare Green Building in China. This evaluation system consists of three indexes, which are the comprehensive index (
Ie), the index of energy saving performance (
Ip), and the index of energy saving level (
Il). The relationship of these three indexes is shown as follows. In this formula, a and b are constant, and their values are 10 and 7, respectively.
4.1. The Index of Energy Saving Level
According to the results of our investigation, we can calculate the average annual total energy consumption (
) of hospital buildings in each bed number range, as shown in
Table 3. Then energy saving level (
) can be got by Equation (2), i.e., the ratio of
to total annual energy consumption of a hospital (
). Then according to the tri-sectional quantile of
Il score, hospitals could be divided into three groups, as shown in
Table 4.
4.2. The Index of Energy Saving Performance
The scores of
Ip were calculated through comprehensive consideration of performances of different evaluation items, such as subentry measures, building automation, air conditioning unit energy-saving, renewable energy utilization, pump frequency control, heat recovery of exhaust air, condensation water recovery, natural cooling, intelligent lighting, energy-saving lamps and reduction in water use. Here, the calculation of
Ip will strengthen consideration on high energy consumption items, such as air conditioning system and lighting system (as mentioned in
Section 2). According to the scores of
Ip, hospitals were divided into four groups, as shown in
Table 5.
4.3. The Comprehensive Index
Finally,
Ie can be calculated by bringing
Il and
Ip of the hospital into the formula 1. As shown in
Table 6, hospitals are classified into four levels. Specifically, three stars (★★★) are awarded for a hospital with the best energy-saving level and performance, while zero star (☆) is for a hospital with the worst energy-saving level and performance.
4.4. Visual Application of Evaluation System
Section 4.1,
Section 4.2 and
Section 4.3 described the evaluation index composition and its calculation procedure, which is affected by many parameters of the energy consumption and energy supply system of hospitals. Therefore, considering the application convenience, this paper further gave visual software as shown in
Figure 13, which can be applied by practitioners evaluating the building energy consumption performance. Practitioners only input relevant parameters of one hospital, and the output will be given by this visual software (
Figure 14).
5. Conclusions
This study carried out a comprehensive energy use investigation of hospitals in China. The investigation results indicate that electricity consumption is the highest in the total energy consumption, which accounts for 64%. Air conditioning system accounts for the maximum share in electricity consumption, especially in south China. Therefore, saving electricity in the south hospital is the most direct way for achieving hospital energy savings.
Then a novel rating system of energy consumption in operation and management for Chinese hospitals was established. This rating system can evaluate energy use performance of a hospital, which also can be compared to another hospital due to using a standard evaluation process. What’s more, this evaluation system can find out weak links of energy use and provide corresponding improving suggestions. Furthermore, to achieve these evaluations, a kind of visual software was given by our paper, which can be easily used by practitioners.
Through the results of this investigation and rating system, some suggestions on energy saving in hospitals were given as follows. Compared with other types of public buildings, the function of hospital buildings is much more complex, and the healthcare environment is under strict control. Therefore, hospital energy saving must start from the concept of comprehensive energy utilization and energy balance. And the traditional measures of hospital energy saving need to be changed and conducted based on the comfort of the healthcare environment. During the expansion of the hospital, the energy supply and demand of the whole hospital should be comprehensively planned to achieve energy balance as far as possible, to improve the efficiency of the system, and to strengthen the heat recovery and utilization. Only in this way, the energy saving in hospital buildings can be realized with the assurance of the service level of the hospital.
Finally, this investigation is only a first step of a more in-depth analysis where energy assessment has to be carried out simultaneously to IEQ investigations.