The review of energy efficiency building regulations in Singapore, Australia and Brazil provided useful insights into their overall structure and underlying objectives. Primarily, the regulations aimed to address the following objectives:
improvement of building fabric or envelope (for heat gain control) reduction of cooling loads (provision for cooling)
integration of renewable sources of energy use of ‘intelligent’ energy management systems
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improvement of indoor conditions while minimizing energy requirements use of energy saving equipment
Overall, it was apparent that the focus of regulation lay in the first two objectives which were directly related to the aforementioned design strategies for hot and warm humid climates i.e. heat gain control and provision for cooling. This was suggested to be due to the fact that they would possibly produce the greatest effect in building’s energy efficiency and that they directly affect the need or extent of the subsequent objectives.
Generally, the development of the energy efficiency regulations in the three countries has revealed their increased uptake, albeit at different rates (Institute for Building Efficiency, 2013). Of the three countries, Singapore appears to have made the most significant strides. The latest available figures indicate that the number of energy efficient building projects grew from 17 in 2005 (mandatory energy efficiency regulation was introduced in 2004) to about 1,600 in eight years. This translates to 47,000,000m2 of Gross Floor Area (GFA), or 20% of Singapore's total GFA. Singapore aims to increase this figure to 80% of its building stock by 2030 (Building and Construction Authority, 2013c). A study of the impact of mandatory regulation on a sample of 36 retrofitted buildings found that the annual total building energy savings per square metre improved by 16% per annum (58kWh/m2/year). These energy savings translated into 85 GWh energy savings per annum, or $22,700,000 in cost savings (Building and Construction Authority, 2013a).
In Australia, a memorandum of understanding between the various states led to the development of the National Strategy on Energy Efficiency (2009-2020) which aimed to maximise energy efficiency measures across the country. As a result, higher energy efficiency standards are applied to an estimated 26,500 commercial building projects constructed each year, as well as the significant number of major building renovations (Council of Australian Governments, 2009, p.3). It was suggested that the introduction of the mandatory Commercial Building Disclosure (CBD) scheme in 2010 requiring all commercial building owners to obtain a Building Energy Efficiency Certificate (BEEC) in 2011 should signal even more significant improvements.
93 Further, the adoption of mandatory approaches to energy efficiency regulations in Singapore and Australia is suggested to have been the prime reason why the development of the energy efficiency regulations has shown increasing growth or uptake.
In Brazil, the implementation of regulations was found to be at a relatively early stage, this made it difficult to judge the impact of energy efficiency regulation to date. However, a recent energy efficiency indicator survey revealed that more building stakeholders in Brazil were keen on incorporating energy efficiency measures (Institute for Building Efficiency, 2012). Given the parallels that can be drawn between Brazil and Kenya, including the lack of stringency in the prevailing construction industry, lack of supporting documentation and the small number of trained professionals in the field, the Brazilian model offers significantly useful insights. For instance, as Kenyan energy efficiency regulations are at a relatively early stage of development, a similar transition from voluntary and to mandatory regulations can provide opportunities to fine tune regulations and time for stakeholders to gain experience.
In the context of energy efficiency and with reference to the inherent nature of building regulations, the reviewed regulations were found to consist of one or two approaches as outlined in Table 2-4.
Table 2-4 Typical energy efficiency regulatory approaches (Australian Building Codes Board, 2010b, Gann et al., 1998, Inter-jurisdictional Regulatory Collaboration Committee, 2010,
Lamberts et al., 2007).
Type Prescriptive Performance-based Trade-off approach Definition Offer a detailed set of
prescriptions that outline how to go about
reaching a certain solution.
Specify the required goal of the regulation so as to bring about a desired function.
Compares a proposed building to a reference building that meets the anticipated
requirements of a prescriptive nature.
Main
Characteristic
Describes the ‘what’ and the ‘how’ of a required standard or code and are deemed mandatory.
Describes the ‘what’ but leaves the ‘how’ open to interpretation thereby allowing for innovative solutions.
Allows for trade-off on building envelope properties. For example, the U-values of different building elements.
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Historically, the prescriptive approach has formed the basis of majority of building regulations (Bell and Lowe, 2000, Inter-jurisdictional Regulatory Collaboration Committee, 2010, May, 2007, Pérez-Lombard et al., 2011). However, the rapid rise in the number of regulated areas and the difficulty involved in attempting to capture all requirements within individual building regulation, as well as the rigid nature of the prescriptive approach, has resulted in the shift towards performance based regulations that allow for greater flexibility of solutions (Inter-jurisdictional Regulatory Collaboration Committee, 2010, Chua and Chou, 2011). In this case, it was suggested that the relatively recent introduction of energy efficiency regulations deemed it reasonable to anticipate evolved or new solutions. This trend is evidenced by the adoption of this approach by numerous building regulatory bodies (Gann et al., 1998, May, 2007), including the BCA in Singapore and ABCB in Australia.
Generally, the reviewed prescriptive regulations consisted of performance indices that were mainly addressed towards AC buildings. These indices offer guidelines on the optimisation of the building envelope performance (such as ETTV) or reduction in energy or electricity consumption (such as EEI and IC). Despite the apparent restriction of prescriptive regulations to AC buildings, it was suggested that they might also be beneficial to employ a similar method to naturally ventilated buildings to serve as a ‘first approach’ method for the optimisation of the building envelope. It was suggested that this might be particularly useful in Kenya; given that such indices are usually relatively easy to use, in contrast to use of modelling software that requires skilled personnel which is currently in short supply.
On the other hand, the performance-based approach tended to be recommended for naturally ventilated buildings. This was attributed to its flexible nature which allowed for greater variation in solutions. With current developments in modelling software solutions, it is possible to run various strategies that would simulate building service systems allowing for greater accuracy in prediction of indoor comfort and energy use. Using modelling software, performance could be predicted and improved upon as required during the early design stages. Whereas this method is not usually recommended for AC buildings, it is suggested that it would also serve
95 to benefit designers who employ it in any type of building, irrespective of ventilation mode.
The choice of regulatory approach was also determined by the local conditions. Brazil, which changed course from the development of fixed prescriptive minimums to the use of a trade-off approach, is one example. This shift was made owing to the foreseen difficulties in ensuring quality of construction and implementation of regulation. This situation bears close similarities to Kenya which has had enforcement issues of its own (Mathenge, 2012); similar issues have been reported in other developing countries (Ofori, 2012, International Council for Research and Innovation in Building and Construction (CIB) and United Nations Environment Programme International Environmental Technology Centre (UNEP-IETC), 2002).
It has been established that the main thermal comfort concern in buildings in hot and warm humid regions arises from relatively high temperatures coupled by high relative humidity (Chapter 1). In Kenya, the effect of these climatic factors combined by poor building design is often overheating in buildings and an increase in cooling load. To address this, energy efficiency regulations need to apply the necessary adjustments to accommodate local climate conditions. For instance, in Singapore, Australia and Brazil, suitable climate-responsive strategies key in achieving suitable indoor conditions were considered (including natural ventilation and sun shading). To further improve the effectiveness of regulation, specifications for building envelope efficiency were found to recommend heat gain control and the provision for cooling.
In addition, it was found that energy efficiency regulations are largely guided by requirements for the given climate, even more so those relevant to naturally ventilated buildings. This was done to increase their accuracy for local use. For instance, prescriptive equations such as IC were developed for each of the eight bio- climatic zones of Brazil, as was ETTV in the case of Singapore. Similarly, by using the simulation approach, one is able to test solutions for specific site locations by running climate specific weather files. This would be especially useful in Kenya where
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the existing wide range of climate zones necessitates the need for climate-specific guidelines.
Numerous thermal comfort field studies have indicated that adaptive opportunities can increase the range of thermal acceptability levels (Cândido et al., 2011b). Similarly, evidence has shown that the more thermally comfortable the occupants of a building are, the less likely they are to resort to active means as a way of meeting their comfort requirements, hence reducing the need for energy expenditure (Bodach and Hamhaber, 2010). However, of the regulations reviewed, thermal comfort was revealed to be more of a potential outcome of energy efficiency rather than as a main objective. Little is mentioned of the improvement of indoor conditions to minimise energy requirements. Given the range of predicted comfort presented in Chapter 1, it is thought that the regulation provided in the three select countries is rather limiting – and especially for naturally ventilated commercial buildings.
In Singaporean regulations, where naturally ventilated buildings are considered, no clear definitions of thermal comfort are made, instead thermal comfort is considered a possible result of building envelope design strategies (shown in Figure 2-13). For AC buildings, comfort is alluded to in relation to indoor air quality and the installation of AC systems; in this case it is recommended that temperature levels of between 24°C to 26°C with corresponding relative humidity of 65% be maintained consistently (Building and Construction Authority, 2012b, p.30).
In Australia, the ABCB categorically state that whereas thermal comfort is desirable, it is neither defined nor are optimum levels provided but rather it is anticipated as a result of improved energy efficiency (Australian Building Codes Board, 2010b). Instead, the ABCB stress that the main drive of energy efficiency regulation is to reduce greenhouse gas emissions and argue that if the building envelope is constructed efficiently then the consequent effect will be occupants being more comfortable than they would be otherwise.
Correspondingly, no specific comfort definition or standard has been developed for the Brazilian climate zones for purposes of labelling of naturally ventilated buildings;
97 instead guidelines recommend use of ASHRAE 55, ISO 7730 or any other adaptive comfort standard, without going into any specifics (INMETRO, 2010). Cândido et al. (2011b) suggests that whereas it would be difficult to provide a unique standard that is suitable for all regions in Brazil (owing to the bioclimatic differences), a more valid approach to indoor thermal acceptance would be through development of a standard that focuses on air movement and thermal comfort. It is suggested that the provision of such a regulation could encourage a shift towards natural ventilation during suitable times of the year and in so doing, reduce energy requirements.
Whereas one may argue that building energy efficiency regulations are, as the term suggests, concerned primarily with energy consumption, the role that provision thermal comfort can play in increasing energy efficiency cannot be ignored. Traditionally, air conditioning strategies have emphasized the management of indoor temperature and humidity conditions through active systems to provide thermal comfort for occupants (as with the case in Singapore). As such, owners or building designers may not typically understand or utilize the broader range of means at their disposal to support thermal comfort, or look to incorporate them into their designs or operation.
Thoughtful building design that makes use of the wider array of available thermal comfort mechanisms and opportunities can be leveraged to result in significant energy savings, whether when evaluating options for a new build or retrofit; or through operational improvements on an existing air conditioning system. It is further suggested that thermal comfort regulations need not be ‘static figures’ leaving little room for manoeuvre but rather guidelines that allow the designer to improve potential for thermal acceptability and comfort as guided by results from local field study recommendations.
Owing to the revival of energy efficiency measures in the 1990s, various assessment methods arose to help improve energy efficiency and minimise energy consumption. These assessment methods are now considered instrumental in driving sustainability within the construction industry from design to post occupancy stages (Haapio and Viitaniemi, 2008, Pérez-Lombard et al., 2009). A review of energy efficiency
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regulation in the selected countries has revealed the prevalence of these environmental assessment methods. Typically, they are used to measure and rate the environmental performance of buildings. Similarly, they outline the criteria through which the performance of a building can be gauged; in most cases this criterion is relative to established benchmarks in the form of guidelines or databases.
Different building rating systems give varying labels and certificates dependant on specific end user needs (Ding, 2008) with many having been developed to apply specifically to the country in which they have been developed, or localised to fit climate and government policies and regulations (Kubba, 2012, Alyami and Rezgui, 2012). Nonetheless, in as much as different criteria have been developed in the aforementioned regulations, the basic themes are recurrent. Table 2-5 presents an overview of the main environmental assessment tools that are recommended as part of building regulation in Singapore, Australia and Brazil. The tools include Green Mark - developed by BCA; NABERS - originally referred to as Australian Building Greenhouse Rating; and RTQ-C which was a product of the PROCEL-Edifica initiative in Brazil.
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Table 2-5 Environmental Assessment Tools Comparison (Building and Construction Authority, 2012a, Green Building Council Australia, 2013, Kubba, 2012, NSW Department of Environment
Climate Change and Water, 2013, Pollis, 2013).
Tool GREEN MARK NABERS RTQ-C Year formed 2005 1998 2006
Climate suitability
Tailor-made for the humid Singaporean climate
Australian climate zones (including warm humid)
Brazil’s bioclimatic zones (including warm humid)
Status Mandatory under the Code of Practice for Energy Efficiency Standard for Building Services and Equipment
Mandatory under the CBD scheme and also by law in Government buildings in States and territories (varies) Voluntary, to be made mandatory Building type Commercial and residential Commercial and residential Commercial Assessment criteria Energy efficiency Indoor Environmental Quality Water efficiency Environmental protection
Other Green Features
and Innovation Energy Indoor environment Water Waste Prescriptive method
(Building envelope pre- requisites and
electricity efficiency)
Simulation method (to
compare the proposal with a reference building or to gauge comfort)
Rating Scales
Certified (lowest rating), Gold, Gold Plus or Platinum (highest rating)
6 stars (Market-leading performance), 5 (excellent), 4 (good), 3 (average), 2 (below average), 1 (poor)
Rating from ‘A’ to ‘E’ from most efficient to least efficient. Post occupancy evaluation provisions Re-assessment required every three years
Ratings reviewed annually Currently labelling is done in just two phases: in the design stage and on building completion to confirm rating
Besides providing a useful framework within which designers can checklist energy efficiency requirements, these assessment tools also promote the certification or labelling of buildings which has encouraged integration into the market sector. A valid example is the CBD scheme in Australia that is designed to improve energy efficiency in commercial buildings by requiring all building owners to obtain and disclose a NABERS rating before selling or renting space. Similarly, in Singapore, commercial buildings are required to obtain a minimum Green Mark rating for which energy efficiency comprises of up to 60% of the score. Of the regulations reviewed, it
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was established that these tools provide a comparatively concise approach within which regulations can be outlined and easily followed through by designers.
The role of environmental assessment tools has grown over the years with more established methods such as BREEAM and LEED having had a significantly wider reach spanning into the developing world. In Kenya, the recent formation of the Kenya Green Building Council has seen the introduction of the Greenstar rating tool which assesses the environmental attributes of new and existing facilities in building industry in Kenya. Where energy efficiency regulations are yet to be fully developed or accepted, it is suggested that these tools could work fairly well in introducing the concept to stake holders without being too overwhelming (owing to their concise approach). Although it is early days yet, the development of a localised tool in Kenya has the added advantage of benchmarking similar type buildings within a local climatic region for comparison purposes that could lead to further improvements in energy efficiency.
2.4 Conclusions
Passive design for climate in hot and warm humid regions requires that buildings are designed to ensure that occupants remain thermally comfortable with minimal need for supplementary cooling. To do so, suitable passive design strategies that address the relatively high temperatures, high relative humidity and solar radiation common to hot and warm humid climates should be applied. In this chapter, it was noted that these passive design strategies can be divided into two groups: heat gain control measures and provision for cooling. In particular, heat gain control measures were deemed to form the basis of passive design in hot and warm humid climate; this is because they work to restrict or minimise heat gain that has the potential to cause discomfort indoors. On the other hand, cooling control measures were suggested to be more remedial in nature; this is because they work to expel heat build-up and provide cooling for occupants.
The prime contributor of heat gain to a building is usually from solar gain. Consequently, where heat gain is undesirable, as would be the case in occupied office buildings in warm humid climates, solar control forms one of the main heat
101 alleviation strategies applied to buildings. This would appear to justify the focus on solar control in a substantial number of design guidelines for warm and hot humid climates and indeed in the limitation of this study to the application of external shading devices for the improvement of thermal comfort and energy efficiency. In addition to solar control, the regulation of conduction gains, ventilation and infiltration gains and internal gains were found to be useful in curbing heat gain in buildings. The extent to which these controls impact heat gain and subsequent comfort is explored in succeeding chapters examining the thermal performance of selected case study buildings.
In addition to solar control, the mitigation of conduction gains, ventilation and infiltration gains and internal gains was also examined. The performance of conduction gains was found to be highly dependent on the exposure and performance of the building envelope. A smaller building surface area led to reduced gains, whereas increased insulation reduced the influx of gains through the fabric. On the other hand, ventilation gains were found to depend on the difference between the outdoor and indoor temperature; this necessitates the control of ventilation when the outdoor temperature is higher than that indoors. On the other hand, infiltration gains were found to be dependent of the airtightness of the building. This is particularly important when designing for AC buildings to prevent a reduction in cooling system efficiency. Internal gains control was attributed to