|Paper presented at the Seminar on Building Codes on
Energy Efficiency, 2-4 December 1997, Hong Kong, organised by the Hong
Kong Institution of Engineers
Macroscopic Analysis of Building Energy Efficiency Standards
|Abstract: With emphasis on the conditions in China,
this paper analyses macroscopically the legal framework, categories and
approaches of building energy efficiency standards. The climatic
factors, socio-economic development and development of the building industry
are discussed to investigate the characteristics of energy standards.
Keywords: Building energy efficiency standards, building energy codes, macroscopic analysis.
1.1 Importance of Building Energy Efficiency2. The System of Building Energy Efficiency Standards
2.1 Energy Efficiency Laws3. Characteristics of Building Energy Efficiency Standards
3.1 Climatic Factors4. Conclusion
Table 1 Existing building energy design standards in China
Table 2 Building Energy Codes in Canada and USA
|Since the global energy crises, building energy efficiency has become
a new limiting factor in building design. Energy efficiency is an
important energy policy and is also an essential way to minimise pollution
and protect the environment. Nowadays, many countries believe that
energy efficiency has close relationship with environmental protection
and economic development, and is a key element for establishing sustainable
The current energy policy in China is "equal emphasis on energy development and conservation, and putting conservation a priority" . If China is to achieve a double-fold in its industrial and agricultural production by the end of this century, half of this production will reply on energy conservation. Therefore, the work on energy conservation is becoming more and more important. As the economy continues to grow and the living standard of the people is improved, building development will increase and the building energy consumption will boost drastically. The tense energy supply has already crippled the economic development and the further advancement of living standard. Thus, building energy efficiency becomes a long-term and pressing task .
1.1 Importance of Building Energy Efficiency
Building energy efficiency is a major part of energy conservation work. In both developed and developing countries, building energy use constitutes a significant portion of the total energy consumption, usually about 25% to 40%. Therefore, almost every countries in the world have placed building energy efficiency in a key position. Excessive energy use in buildings will not only waste natural resources, but also bring about adverse environment impacts like greenhouse effect and climate change. This will threaten the sustainable development of the community and the world, and the situation must be looked at seriously and put under control.1.2 Problems in the Development of Building Energy Efficiency
Building energy efficiency spans over a wide range of subjects and requires skills in many different areas in order to improve the policies, technologies and management. Although building energy efficiency standards have already been implemented in China, when they are compared with standards in other advanced countries in the world, there is a large gap between them . The major problems at present include:
|2. The System of Building Energy Efficiency Standards|
|Building energy efficiency standards and codes can contribute to the
promotion and demonstration of efficiency matters which raise the importance
of energy efficiency work and ensure that efficiency technologies will
be applied and developed . To analyse
building energy efficiency standards, one should first look at the legal
framework, categories and approaches.
2.1 Energy Efficiency Laws
Developing the work on energy efficiency requires strong legal support . Establishment of legal framework can have significant effects on monitoring and direction, and is very important to building energy efficiency. Therefore, a high-level national energy efficiency law will often form a good foundation for the development of energy efficiency. For example, the Energy Policy Act 1992 in USA, the Energy Efficiency Act in Canada and the Law on Efficient Utilisation of Energy in Japan are famous national energy laws. Because of the differences between the countries and their legal systems, the format of the energy laws may be different . However, the overall objectives are the same: to promote through legal intervention the effective development of energy resources, reduce energy use and increase economic efficiency.
As for building energy efficiency, the "Temporary Regulations on Energy Efficiency Management" issued by the State Council in 1986 is the most important document so far and Article 35 of the Regulations reads "Building design, provided the an acceptable indoor living environment is ensured, should adopt integrated measures to determine efficient shape and orientation, to improve its building envelope, to select equipment with low energy consumption and to utilise natural light sources; so as to reduce energy use in lighting, heating and refrigeration". In recent years, the Ministry of Construction has also issued the "Building Energy Efficiency's 'Ninth Five-year Plan' and 2010 Strategy" which lists out the basic goals on building energy efficiency . To achieve all these principles and goals, there should be other technical codes and standards developed to provide the energy efficiency requirements, energy targets and design guidelines. This is the starting point for building energy efficiency standards.
There are many different types of building energy efficiency standards and they have their own characteristics which origniate from their locations, societies and environments. China and other foreign countries have different definitions on the scope of building energy use. In China, it may include energy for the production of building materials, the construction process and the building's usage, therefore, it will cover both the areas of industrial production and people's living . In western countries, the energy use in buildings usually refers to the energy of using the building, including heating, air-conditioning, lighting, hot water supply, electric appliance and cooking. Common building energy efficiency standards can be classified according to their building functions, such as residential, commercial, hotel and industrial buildings. In some countries the standards are divided into federal (or government) buildings and private (or civil) buildings. Currently, most of the building energy efficiency standards are designed for new buildings and very few of them are prepared for existing buildings. Table 1 shows the contents of the two existing building energy design standards in China [10, 11] and Table 2 shows the contents of the building energy codes in Canada and USA [12, 13]. By comparing their contents and scopes, we may appreciate their differences. In general, their applications and approaches are not the same; the codes in Canada and USA are more advanced, have higher energy efficiency requirements and consider more aspects (such as lighting and electric power); they also provide different paths for designers to comply with the requirements.
Table 1 Existing building energy design standards in China
Table 2 Building Energy Codes in Canada and USA
Strictly speaking, codes and standards affecting building energy efficiency are not limited to building design and may include other related regulations such as the standards for testing of energy efficiency products and building materials, the standards for testing electric appliance and equipment, the codes and policies on energy efficiency management and the regulations for the plans of energy efficiency loans. Because energy efficiency research requires the integration of knowledge from many different disciplines including energy, environmental, economic and social subjects, the overall macroscopic control of building energy efficiency will involve many government departments, such as the State Planning Commission, the State Economic and Trade Committee, the State Scientific Committee, the Ministry of Construction, the Council on Building Materials and the Council on Inland Revenue. To achieve the best result on energy efficiency, each department should coordinate among themselves and cooperate on different tasks. The establishment of a specialised institute on energy efficiency to coordinate all the related works may help focus the resources and power.
Building energy efficiency standards usually include many technical requirements and details. If it is required to codify the standard, its structure, words and contents may have to be studied carefully and simplified so as to make it acceptable by the legal system. To keep the legal power of the document as well as the technical details is not easy. It will also take a lot of time to complete the drafting and legal process. During the discussion on mandatory and voluntary standards, some people have suggested the use of voluntary standards because they are more flexible and cannot be set up first with much less time (they may be amended and codified afterwards).
The general purpose of building energy efficiency standards is to ensure that the "minimum' efficiency requirements are met so as to achieve the efficiency goal. However, a higher-level objective of the standard should be the encouragement of better than the "minimum" requirements in order to enhance the level of building energy technologies. More often than not, the significance of some building energy standards lies on their ability to raise efficiency awareness and concern, rather than the achievement of minimum requirements . In the analysis of the effects of building energy standards, one should not only look at their scientific and economic achievements, but also at the social factors and forward-looking features.
Nowadays, building energy standards have two main characteristics: prescriptive approach and performance-based approach . Prescriptive approach specifies the minimum requirements for each building component to satisfy the standards, such as the maximum heat transmission coefficient of exterior walls and the minimum equipment efficiencies. Performance-based approach sets a maximum allowable energy consumption level without specifying the methods and materials to be employed to achieve it; therefore, architects will have greater design freedom and may overcome the limitation of prescriptive requirements. Usually, the standards in the past and many of the existing standards are prescriptive in nature because the implementation is simpler and easier. However, in order to allow greater design freedom and achieve better energy efficiency, some advanced countries tends to develop performance-based standards, such as in USA, Canada and New Zealand . By adopting comprehensive energy performance approach, we can encourage innovative, flexible and integrated energy design in buildings. The biggest problem with this approach is the difficulty to evaluate the building energy performance.
|3. Characteristics of Building Energy Efficiency Standards|
|By studying the characteristics of building energy efficiency standards,
we may determine better energy codes which are suitable for the local environment
and develop energy efficiency work to upgrade the building technologies.
3.1 Climatic Factors
Building energy consumption has close relationships with the ambient natural environment like sunlight, temperature and wind conditions. The practical strategies for building energy efficiency will wary with the climates at different locations. In fact, the basic principle of energy efficient buildings is to make the best use of the local climatic resources and natural conditions so as to provide a comfortable indoor environment. Classification of climatic regions and the study of their effects on building design are the prime factor in building energy standards. Current building energy standards often set out the general strategy, prescriptive requirements and energy targets according to the climatic regions. In China, the climatic classification for building energy efficiency is made based on thermal design standards and will involve mainly the consideration for thermal insulation in winter and summer . At present, China is divided into five types of climates, namely, very cold, cold, hot-summer-cold-winter, hot-summer-warm-winter and warm. To determine effective requirements for building energy efficiency, one must first investigate the characteristics and cycles of the local climate . Climatic boundaries are not strict rules for system selection and design, and they should be flexible enough, otherwise people will tend to ignore them. Research on the properties of building climates and climatic data can help to improve the energy standard and establish requirements for local conditions.3.2 Socio-economic Development
Energy demands are directly related to socio-economic development and the energy consumption patterns are often used to determine the strategy for building energy efficiency. When building energy standards are being developed, the most important energy users of the society will be considered first. Thus, we may observe the changes in local economies, people's living and building technologies by studying the development of the energy standards. From a national point of view, energy standards and policies should work in line with the overall economic development and for the benefit of the society. The economic system of China is now in its transition stage, changing from a production method with high consumption and low efficiency to the focus on resource efficiency and improved performance . With the growing of economic development, heated building areas are expanding and air-conditioned buildings are increasing very fast. This has resulted in a growth rate of building energy use higher than the growth rate of energy production. The building energy consumption in China boosts drastically and the potential for building energy efficiency is tremendous . This will offer a good opportunity for transforming the economy and promoting future development, but the establishment of building energy standards must be accelerated and enhanced.
Building energy efficiency has a very strong local character and every places will have to develop their policies and regulations according to their conditions and needs. Therefore, when building energy standards are being implemented, they should be amended and adapted to the local situations. For example, many of the states in USA have developed their own building energy codes according to the requirements of the federal energy law . In USA when the states established their energy codes, they often refer to some basic building energy standard such as ASHRAE , BOCA  and CABO . However, a few states such as California and Florida are more progressive and have carried out their own research to develop building energy codes which employ more advanced techniques. This "basic standard/localised code" approach to develop energy codes may be more effective than a nation-wide standard when applied to a large country because every places may have their particular problem in energy efficiency. At present, the relationship between the Hong Kong Special Administrative Region and the Mainland China is quite interesting and they have their own sets of building energy regulations and standards . But for long-term development it is very important to coordinate these standards and develop mutual understanding.
The building industry will develop with the modernisation and urbanisation of the society. As the urbanisation and the development of cities/towns is getting fast and the people demand for better indoor thermal environment, the energy consumption in cities (including energy use in domestic, commercial and municipal facilities) will increase drastically. If the problem of rural energy is separated from the issue, building energy efficiency will usually concentrated on the following areas: building envelope, heating, ventilating and air-conditioning (HVAC) systems, lighting systems, hot water supply systems, electrical distribution system and cooking. The heating and hot water in winter and the HVAC in summer are the most important. Thermal insulation standards may be treated as the earliest generation of building energy standards, but as building technologies advance and get complicated, building energy efficiency is no longer a problem about thermal insulation only. The emergence of building energy efficiency has induced many changes to the technologies, products and organisation in the building industry . The contents, approaches and requirements of building energy standards will also have to be upgraded in order to catch up with the development of technologies, the worldwide trends and the needs of the society.
The existing building energy standards in the Mainland China focus on heating and hot water of residential buildings . The residential buildings in China have poor thermal insulation at their building envelopes which results in undesirable indoor thermal environment and large heating energy requirements. Low-efficiency heating method using coal is still very common and has given rise to significant air pollution. Therefore, household energy efficiency is the major problem that China is trying hard to solve . The situation in Hong Kong is very different. The existing and proposed building energy codes in Hong Kong aim at commercial and hotel buildings . The control of energy consumption of air-conditioning and other building services equipment in high-rise buildings is the most important concern and this reflects the characteristics of hot climates and commercial urban cities. However, the current building energy codes in Hong Kong are weak in technological support and do not have enough verification and field testing yet. Thus, these codes should be improved and strengthened in the future .
With fast development of hotel buildings, office buildings, institutional buildings and air-conditioned households, "air-conditioning fever" is growing quickly in the Mainland China and has become the main reason for the acute increase of building energy use in some locations. This is particularly important for fast-growing cities, like Shanghai . Air-conditioning usually consumes a lot of electricity and its loads have a large variety throughout the day and the year. This will create great pressure to the electricity supply network. The electricity industry in China is developing very fast in recent years but the supply of electricity is still very tense, especially in the east coastal regions. The shortage of energy and electricity supply will directly affect commercial activities and people's living. The more serious this shortage problem is, the more urgent is the need to improve air-conditioning energy efficiency. In general, air-conditioning energy efficiency is more complicated than heating systems and the technologies are also developing very fast . The experience from the western countries suggests that to tackle the energy efficiency of air-conditioning systems, building energy standards will grow in complexity and will have to consider at the same time other factors like lighting systems, daylighting, internal equipment and solar energy systems. To due with the problem of peak demand, thermal storage systems may be employed to shift the daytime peak loads to night time and other measures to control the peak electricity demand may be used.
The future trends of building energy standards, including performance-based approach, the use of computer software and building energy simulation techniques , are aiming at improving the energy efficiency, creating greater design flexibility and encouraging innovative building energy designs. To achieve these objectives, we need not only to develop advanced building energy standards, but also to rely on the support from the building professionals. Strengthening of the education on building energy efficiency and providing training to the related professionals such as architects, engineers, planners and managers will help to improve the research and management teams for building energy efficiency . Technological advancement is the key to achieving better building energy efficiency. Building energy standards should be treated as a catalyst to promote the development of building technologies, which facilitate ourselves to implement actions for sustainable development.
|Building energy efficiency spans over a wide range of subjects and
should be planned carefully. This paper analyses macroscopically
the system and characteristics of building energy efficiency standards.
It is hoped that this could help readers to develop a better understanding
of the issues and the relationships. Building energy efficiency is
very important to the conservation of natural resources, environmental
protection and social development, and is the key element for achieving
sustainable development in the 21st century. To promote
healthy development of the building energy efficiency industry, building
energy standards should be enhanced. The energy efficiency works
in China (including the Hong Kong Special Administrative Region) started
at a time later than the advanced countries in the world. The
most important issue at present is to study and develop the building energy
standards which will suit the local environment. To catch up with
the building energy efficiency level of advanced countries, more reforms
will be required. The tasks in this area require us to investigate
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