Green Building Assessment Standards And Construction

Discuss about the Green Building Assessment Standards and Construction.

Green Mark Ratings

There are four main Green Mark Ratings. These ratings are based on the Green Mark Score awarded to a building. The four ratings are as follows: Green Mark Certified – Green Mark Score of 50 - <70), Green Mark Gold – Green Mark Score of 75 - <85, Green Mark Gold^Plus – Green Mark Score of 85 - <90, and Green Mark Platinum – Green Mark Score of 90 and above (Building and Construction Authority, 2016). The Green Mark Score is the total of scores awarded to different elements of the building that make the building to be energy efficient, water efficient, environmentally friendly, and have high indoor environmental quality and other appropriate green features (Building and Construction Authority, 2018). In this problem, the owner of the building is planning to retrofit an existing 8-storey office building so as to make it more resource efficient and sustainable for it to achieve Green Mark Platinum rating under the BCA Green Mark for Existing Non-Residential Buildings (Version 3.0). A scorecard showing the scoring of the building under BCA Green Mark for New Non-Residential Buildings (Version NRB/4.1) has been provided. Relevant information has to be extracted from this scorecard and used to determine the score of the building under BCA Green Mark for Existing Non-Residential Buildings (Version 3.0). This will help the owner identify appropriate areas that should be improved and determine the best strategies of improving them so that the building can achieve Green mark Platinum rating after retrofitting.

The current scoring of the building based on BCA Green Mark for Existing Non-Residential Buildings (Version 3.0) is provided in Table 1 below:

Table 1: Current scoring of the building

The Green Mark Score of the building based on BCA Green Mark for Existing Non-Residential Buildings (Version 3.0) is 90.56, as shown in Table 1 above. This is slightly above the Green Mark Score of 90 needed for the building to be awarded with Green Mark Platinum rating. Therefore based on overall Green Mark Score, the Green Mark Rating of the building is Green Mark Platinum. However, it is important to note that the points located for different categories of energy efficiency and other green requirements/features were based on the scorecard points awarded to the building when it was analyzed under the BCA Green Mark for New Non-Residential Building (Version NRB/4.1). There are some elements that were not awarded any point because of insufficient information from the previous scorecard. This is because there are some energy efficiency and other green building requirements included in the BCA Green Mark for Existing Non-Residential Buildings (Version 3.0) but missing in the BCA Green Mark for New Non-Residential Building (Version NRB/4.1), and vice versa. The elements that did not have adequate information from the provided scorecard were not awarded any point. The total points that were not awarded any point are 15. Thus if these points are excluded from the total score, the Green Mark Score of the building is equivalent to 98.79. This overall score rates the building as Green Mark Platinum. The total points from energy efficiency is 53.14, which is more than the required minimum of 45 points hence the building meets the requirement of Green Mark Platinum rating. Other requirements such as minimum efficiency of water-cooled chilled-water plant and unitary air-conditioner or air cooled chilled-water plant systems, and the percentage of natural ventilated areas facing North and South cannot be established from the provided information.

Scoring System and Requirements for Achieving the Green Mark Platinum rating

As the owner plans to retrofit the building with an aim of ensuring it attains Green Mark Platinum rating, he should focus on improving all areas that did not achieve maximum points allocated and the new elements that were not originally included in the BCA Green Mark for New Non-Residential Buildings (Version NRB/4.1).

From the scorecard of the building based on BCA Green Mark for New Non-Residential Building (Version NRB/4.1), the total score of the building was 94.77, which exceeds the minimum score of 90 that is needed for Green Mark Platinum rating. Nevertheless, the building was awarded with Green Mark Gold^PLUS and not Green Mark Platinum because of several reasons. Two of these reasons are as follows:

The first reason is that since the building is air-conditioned, it was required to have a minimum score of at least 5 points under NRB 3-1 Sustainable Construction for it to be awarded Green mark Platinum (Building and Construction Authority, 2013). However, the building’s score under NRB 3-1 Sustainable Construction was 3 and therefore it did not meet the requirements for Green Mark Platinum rating.

The second reason is that since the building is air-conditioned, it was required to have a minimum score of at least 4 points under NRB 3-2 Sustainable Products for it to be awarded Green mark Platinum. However, the building’s score under NRB 3-2 Sustainable Products was 3 and therefore it did not meet the requirements for Green Mark Platinum rating.

Because of insufficient information available, it is not possible to establish if the building met other requirements for Green Mark Platinum rating such as if at least 30% energy saving was as a result of energy efficiency improvements and measures that were put in place to decrease cooling load requirements of the building.

The pre-requisite requirements for a building to be awarded the Green Mark Platinum rating as per the BCA Green Mark for Existing Non-Residential Buildings (Version 3.0) for a fully air-conditioned of cooling load equal to or greater than 500 RT, using a water-cooled chilled water system include the following:

For a building to get Green Mark Platinum award, it must have a total Green Mark Score of 90 and above. This score is the sum of scores allocated to energy efficiency, water efficiency, sustainable operation and management, indoor environmental quality and other green features. 

The building should get a score of at least 45 points from part 1 – energy efficiency category. The various elements under energy efficiency and their respective maximum points are as provided in Table 2 below. This basically means that the building should have components, systems, features, appliances, properties and practices that minimize energy consumption at different stages of its lifecycle.

Table 2: Elements of energy efficiency

Therefore out of the 89 points, the building should attain at least 45 points for it to get Green Mark Platinum award. This means that the owner has to improve each of the elements included in Table 2 above to ensure that they consume as less energy as possible. Since the minimum Green Mark Score for Green Mark Platinum award is 90, the other 45 points should be allocated from the other elements of water efficiency, sustainable operation and management, indoor environmental quality and other green features.

Since the building is using a water-cooled chilled-water plant and its cooling load is, the efficiency of the plant should be at least 0.65 kW/RT. This means that the owner has to consider performance efficiency when selecting the water-cooled chilled-water plant.

Permanent measuring instruments should be installed to monitor operating system efficiency of the water-cooled chilled-water plant. The M&V instrumentation provided should be able to calculate the resultant operating system efficiency of the plant in kW/RT within a percentage difference of 5% with the actual value. The M&V instrumentation should also do the calculations as per the guidelines provided in ASHRAE Guide 22 (ASHRAE, 2012) and AHRI 550/590 (AHRI, 2015). The accuracy of the M&V instrumentation should also be verified by performing heat balance test on the water-cooled chilled-water plant.

At least 75% of the occupied areas that are naturally ventilated should have effective cross ventilation with their window opening facing South and North.

A full indoor air quality audit should be conducted after every three years. The audit should be carried out in accordance with the guidelines of NEA for good indoor air quality in office premises. The audit can also be conducted in accordance with the indoor air quality for air-conditioned buildings guidelines of SS554:2009 code of practice. 

AHRI. (2015). AHRI Standard 550/590 (I-P). Arlington, VA: AHRI.

ASHRAE. (2012). ASHRAE GUIDELINE 22 Instrumentation for Monitoring Central Chilled-Water Plant Efficiency . Atlanta, Georgia: ASHRAE.

Building and Construction Authority. (2013). BCA Green Mark for New Non-Residential Buildings Version NRB/4.1. Singapore: Building and Construction Authority.

Building and Construction Authority. (2016). BCA Green Mark for Existing Non-Residential Buildings Version 3.0. Singapore: Building and Construction Authority.

Building and Construction Authority. (2018, October 5). BCA Green Mark Assessment Criteria and Online Application. Retrieved from Building and Construction Authority: https://www.bca.gov.sg/GreenMark/green_mark_criteria.html