Appraisal of Water Efficiency in Green Building Rating Systems

Anuradha Samarajeewa Waidyasekara
B.Se. (Hons) QS, M.Sc. (Civil Eng), AIQS (SL), MAIQS, AP(GBCSL), SEDA (UK)



Building environmental assessment tools have become widespread in recent years and provide huge opportunities for the green concept to be integrated into a country’s development. These tools are commonly associated with the use of green technology especially to reduce energy consumption, indoor cooling, water saving, reduce wastage, materials etc. The concept of green construction or sustainable construction attracted the construction sector too. Therefore, at present, construction industry is one of the industries talked more on sustainable and environmental performance. Thus, use of environmental tools to measure project performance becomes a compulsory item in industry stakeholders’ project agenda. Rating systems encourage a long term view of sustainability of buildings and these address key sustainable parameters: energy, water, site, indoor environmental quality and materials throughout the project life cycle. The first step in the process of establishing evaluation tools or techniques is to set forth the issues that are encompassed by sustainable construction.

Water conservation is one of the global dilemmas identified in recent past. In recognition of water being a limited and valuable resource, the sustainable assessment systems seek to effectively manage action towards water use efficiency during the project life cycle. McComack et al (2007) identified that an enormous amount of water is used to operate buildings, a considerable amount is also used for extraction, production, manufacturing, delivery of materials to site and the actual on-site construction process. Thus, this article discusses how many credits are given for efficiency and conservation of water in green building rating systems (GBRS) to sustain water resources for the future generation. The data was analyzed considering inputs of six green rating systems such as BREEAM-UK (the longest history), LEED-US (popular and widely used), and few rating systems in Asia: GRIHA-India, Pearl BRS-Abu Dhabi, Green Mark- Singapore and, GreenSL – Sri Lanka.

Definitions for sustainability environment

There are many definitions available on sustainability environment; the article provides the most accepted and popular definitions on sustainability, sustainable construction and sustainable/green buildings. Brundtland (1987) defined sustainability as “meeting the needs of the present without compromising the ability of future generations to meet their own needs”.

Kibert (1994) defined sustainable construction as “creating a healthy built environment using resource efficient, ecologically- based principles”.Hill and Bowen (1997) defined the term sustainable construction as “a process which starts well before construction ‘per se’ (in the planning and design stages) and continues after the construction team has left the site. Thus it includes managing the serviceability of a building during its lifetime and eventual deconstruction and recycling of resources to reduce the waste stream usually associated with demolition”.

Sethi (2001) defined sustainable building as “an efficient, productive, comfortable, safe and healthy environment that supports the business needs of the occupants”.

A concise definition of a green building is provided by ASTM standard E2114-04 (2004) as “a building that provides the specified building performance requirements while minimising disturbance to an improving the functioning of local, regional, and global ecosystems both during and after its construction and specified service life”.

Green building rating systems

Several green building rating systems have been developed to objectively evaluate energy and environmental performance that spans the road spectrum of sustainability (Gowri, 2004). These criteria explicitly promote a future perspective into the code for sustainable buildings. There are many terminologies used to describe assessment criteria. Environmental assessment systems or tools (Boonstra and Pettersen, 2003), building environmental assessment tools (Sev, 2009a; Wallhegan, 2013), sustainable building assessment systems (Fowler and Rauch, 2006), Gibberd, 2005) green building rating systems (Gowri, 2004), building performance assessment methodologies (Sinou and Kyvelou, 2006) and green building assessment tools (Ali and Nsairat, 2009) are some of the common terminologies used by many scholars to explain rating systems which have been developed for measure or evaluate performance of projects under sustainable development, although each gives similar meaning and interchangeably used in the literature. As stated by Gowri (2004), green building design challenges go beyond the typical building code requirements to improve overall building performance and minimize life –cycle environmental impact and cost. It was found terminologies, structure of rating systems, relative importance of the environmental categories, and documentation requirements for certification differed from one given to another rating system. This is because each country is launching indicators/parameters for its own market even though there are some similarities. In general, Site, Water, Energy, Materials and Indoor Environment are the key environmental categories focused in the assessment tools addressing building design and life cycle performance (Gowri, 2004). Each category has a number of prerequisites and requisites criteria. All the projects must meet all the prerequisites to qualify for certification because prerequisites are critical since no credits points are allocated towards the overall score but must be met irrespective of meeting other credit requirements. Requisite means credits have been already assigned for specific criteria and which will impact on total credits gained for the final project award.

The field of building environmental assessment has developed remarkably since the introduction of Building Research Establishment’s Environmental Assessment Method (BREEAM) in 1990. Leadership in Environmental and Energy Design (LEED) is the most popular and widely used green building assessment tool for buildings. It was first introduced in 1998 in the US (USGBC, 2013). As Gowri (2004) mentioned, later many rating systems were developed based on the original international rating systems such as LEED and BREEAM, or integrating few other rating systems. BREEAM Canada, BREEAM Greenleaf, LEED India are examples of such efforts. Green Sri Lanka rating system (GreenSL) was also originally developed incorporating the most popular rating system of LEED by the Green building council Sri Lanka in 2010.

The study evaluated six GBRS. Table 1 depicts the highest credits received for sustainable parameter and the rank received for the ‘water efficiency’ from the total parameters considered in each GBRS. Except GreenSL rating systems, ‘energy section’ received the highest according to the credits allocation. This shows that energy efficiency is a major component of green buildings. The priority level given for water differs from rating system to system. Pearl – BRS was given the second place while Green Mark and GreenSL are given the third place for the water section. BREEAM has been given the least priority level compared to other GBRS.

Table 2 summarises credit distribution of water efficiency and conservation of each GBRS. It was identified ten main requirements under the water section. In general, all systems are allocated more credits for limit or eliminate the use of potable water for landscaping and irrigation purposes, water recycling and water efficiency in HVAC. Further, each system encourages rainwater harvesting, and use of grey water, and condense water as an alternative source to reduce potable water consumption.

It is apparent in Table 2, Pearl- BRS is assigned the highest points i.e. 43 out of 180 for the ‘precious water’ which represents 23.9% from the total. The main reason may be that the Middle East Region’s and neighboring countries such as U.A.E. and Qatar are fast developing countries. Their main problems are water shortage and high temperatures during summer although blessed with huge oil reserves. GreenSL, and GRIHA- India came to the second and third place respectively and their percentages are shown as 19% and 14.4% respectively. 

As stated by Boonstra and Pettersen (2003), rating systems are designed to reflect the different phases in the building life cycle. However, during the evaluation of six GBRS, it was found that from the project life cycle, in-use phase is well addressed by all the rating systems. Further it was revealed that only two rating systems, namely Building Research Establishment’s Environmental Assessment Method (BREEAM) of UK and Green Rating for Integrated Habitat Assessment (GRIHA) of India, have included water efficiency criterion during the construction phase in their assessment criteria. Since construction is considered to be a water intensive industry, its inclusion in environmental assessment tools will be an effective way of controlling it. For instance, the simple step of effectively monitoring water use on site will deliver direct benefits to all concerned. As stated by Gowri (2004), though energy efficiency is a major component of designing a green building, several other basic sustainability requirements (e.g. water) need to be met before claiming the additional credits for energy efficiency. Currently, water was just considered to be another input in construction projects. However, as stated by Kibert (1994), construction industry must change its historical methods of operating with little or no regard for environmental impacts. It should embrace a new mode where environmental concerns should become a centerpiece of its efforts.

Concluding remarks

Objective of sustainability is to avoid or minimise any damaging future consequences from current consumption and investment activities. This paper attempts to simplify how and to what extent green rating systems address the water element in order to sustain water resources for the future generation. From the comparison of the six GBRS, it was found out there exist the different importance level, structure, and credit allocation between each system. It was identified that intention of each green building rating system is to reduce water and use of waste water technologies to reduce or eliminate the use of potable water during the project lifecycle. Reducing building water use through encouraging efficient plumbing fixtures and fittings, water recycling and reuse, monitoring, innovative wastewater technologies, water quality, efficient water use in landscaping and during construction are some headings addressed by each system.

Some GBRS included prerequisites for water section, LEED and Pearl BRS are examples for such systems. It is pertinent to note that all the rating systems have well addressed water conservation methods during the in-use phase and credential given for the construction phase is directly addressed by only few rating systems. Previous studies have shown that construction industry and its activities have significant effects on the environment and construction activity makes extensive use of natural resources including water. Thus, although green building rating systems are designed to promote and integrate whole building design while reducing environmental impacts, in terms of water efficiency and conservation, existing criteria should be reviewed and refined according to the project life cycle. Then, rating systems can be used as a standard method of measurement for green buildings.


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This article is developed from the ongoing research study. The author would like to thank supervisors, Prof. Lalith De Silva and Dr. R. Rameezdeen.