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Sustainable future through the lens of the Green rating system

Sustainability Outlook, IPCC 6th Assessment Report and Green Mark 2021

Major changes are coming to Singapore #GreenMark (GM). It takes the form of the new and improved Green Mark 2021 framework which demonstrated the government and private sectors' foresight and timely release of the pilot version just a few months before #IPCC's sixth assessment report despite an ongoing government-wide effort tackling the COVID-19 pandemic. Green Mark is Singapore's sustainable building certification scheme which has been widely adopted in Singapore and abroad. Though a voluntary scheme for promoting excellence in building sustainability, the requirements typically transit into regulatory requirements as industry adoption increases, also newer, better technology solutions become available.

This article will examine some of the recent developments in the global sustainability scene to provide the context for GM: 2021. We appreciate the alignment between the new Green Mark and the global agendas. We also analyse the difference between previous GM versions and GM: 2021 to support the industry transition towards a more holistic rating system.

It is necessary to know the facts we are dealing with and understand why we are doing it. Almost nobody argues about the effects of climate change (especially in Singapore which is surrounded by the sea and have 25% of her landmass reclaimed from it), but it is different from just knowing climate change is there, to appreciating how bad things could potentially be.

The Background

This global movement starts from the observation and awareness of global warming as shown in the diagram below. Currently, We are about 1-degree celsius from the 1961-1990 average.

Diagram 1: Average Temperature anomaly, Global (interactive chart)

The "zero-line" is the average temperature from 1961 to 1990 (not that there is no global warming during this period but the scientific community has chosen this period as a baseline case). Humanity's industrialization process has been credited as one of the causes of global warming and the industrial revolution began in England in the late 1750s. Hence, by comparing our present-day performance to 1961-1990 averaged levels, we are giving ourselves some leeway and discounted the human-caused temperature increases from before the 1960s.

"So what is so serious about just 1 degree? Our air-conditioning can easily overcome that."

As it turns out, we can't. Because one degree is a global average, the temperature increase is not constant throughout the globe.

temperature anomaly
Diagram 2: Local temperatures in 2019 relative to the average temperature in 1951-1980

As seen above, it is obvious that larger temperature anomalies are concentrated in the polar regions where the ice caps are. Polar ice caps melting is one of the causes of global sea-level rise. But wait, there is more. Comparing sea temperatures and land temperatures, most of the land areas see more significant temperature increases compared to ocean areas. Again, this is not uniform throughout the globe. It is not surprising for North American residents to claim they hardly feel temperature increases because indeed they haven't, in fact, it has cooled a few degrees.

"And so we have established that global warming is indeed happening, some places have it worse than others and the sea levels are rising, but can we be sure that humanity's actions are the cause of this?"

We can! The IPCC report has modelled the temperature scenario due to natural causes only and compared it to observed temperature patterns (with human influence) and it has sharply deviated upwards. It is all too probable that our activities are the cause of it.

Source: IPCC AR6 Working Group 1: Physical Science Basis, Summary for Policy Makers
Diagram 3: Changes in global surface temperature relative to 1850-1900. Source: IPCC AR6 Working Group 1: Physical Science Basis, Summary for Policy Makers

Scientists have identified that Greenhouse Gases, the chief of which carbon dioxide (CO2), is responsible for trapping heat within our atmosphere and is one of the causes of global warming.

Diagram 4: Annual total CO2 emissions by world region

Comparing diagrams 3 and 4, the correlation between CO2 emissions and global temperature increase is obvious.

"So the world is warming up due to human activities, but so what? How is it going to affect me?"

We often describe natural weather phenomenon in terms of 1 in X number of years. A 1 in 10 years 'heavy rainfall' event means in any one year, there is a 10% (1/10) chance of heavy rainfall occurring. Take the example of diagram 5's top-left scenario. In present terms, there is a 28% (2.8/10) chance that we experience a hot temperature extreme in any given year. If we do not curb global warming and edge into the 1.5 degrees scenario, it becomes a 41% chance. At the 4 degrees scenario, it is almost guaranteed that we will experience temperature extremes yearly. The combination of a higher frequency of occurrence and greater severity when extreme weather events occur holds for rainfall and droughts.

Diagram 5: Projected changes in extremes are larger in frequency and intensity with every additional increment of global warming
Source: IPCC AR6 Working Group 1: Physical Science Basis, Summary for Policy Makers

It is worth noting that a lot of existing disaster relief infrastructure was built with the assumption of 1 in 10, or 1 in 50 years return period based on data before climate change became widely adopted and accounted for. We can expect that these resources will be stretched to the limit and in some cases depleted. They simply ain't designed to handle the higher frequency and greater severity emergencies.

We encourage everyone to read the IPCC's 6th assessment report, at least the Summary for Policy Makers, and if possible, the Technical Summary.

"But we are doing something about it right?"

We know from diagram 5 that we want to keep global warming to as little as possible, reversing it would be even better though extremely difficult. Unfortunately, what we are currently doing will result in a warming of about 3 degrees, and with what everyone is promising to do soon, that would still only be 2.4 degrees warming. We need to do better. Much better. (the colour bands represent probability cones where the actual situation will most likely fall somewhere within the cone depending on decisions made)

Diagram 6: Global GHG emissions and warming scenarios
Diagram 6: Global GHG emissions and warming scenarios

"Reducing GHG emissions to achieve the 1.5 degrees pathway is imperative but why should we target the built sector? "

Energy consumption accounts for the majority of the emissions and within that, energy use in buildings contributes 17.5% of total GHG emissions (8.6 billion tonnes CO2, 1 ton is the equivalent weight of 400 bricks, and 1 billion is 1,000,000,000).

Diagram 7: Global GHG emissions by sector
Diagram 7: Global GHG emissions by sector

These are just commercial and residential buildings. Our industries are housed in buildings. Aeroplanes need airports, ships need docks, repair facilities and more. Numerous purpose-built structures can contribute to energy efficiency and overall GHG reduction through simple things like requiring less maintenance, more efficient working route planning to reduce movement within the manufacturing facilities or even shorter routes within the supply chain.

Well-designed buildings, which takes into consideration site context, sources of building materials, the construction process and building performance can have far-reaching impacts beyond the mere 17.5% stated in Diagram 7. In our opinion, GM:2021 is positioned to reach across supply chains, engage stakeholders and punch beyond buildings' apparent weight.

"How well is Singapore Green Mark 2021 aligned to global agendas?"

We see alignment on 3 levels: national, sectoral and global. National alignment with the Singapore Green Plan, sectoral alignment with the most recent World Green Building Council strategy and global alignment to United Nations Sustainable Development Goals (UN SDGs).

The Alignment

The Singapore Green Plan 2030 #GreenPlan.

The core belief of the plan is sustainable development with the vision to achieve net-zero emissions for Singapore as soon as the island city-state can. We have summarised key targets from the 5 pillars of the plan and their relevance to the built sector:

Table 1: Targets of significance to built sector within the Green Plan


Key Target


City in Nature

  • Every household living within 10 mins walk of a park

  • One million more trees are to be planted by 2030 on streetscapes, gardens, parks, park connectors, nature reserves, among others.

  • Residential building integration with services and connectivity to nature will be emphasised from the concept design stage.

  • Development landscapes might be roped in to contribute as well. Tree removal and building setbacks might become more stringent.

Energy Reset

  • Building's 80-80-80 by 2030 plan

  • Switch to EV

  • Green Energy

  • Almost all new developments will have to achieve at least GM Gold Plus certification.

  • Provision of EV charging and installation of solar PV will be greatly encouraged where feasible.

Green Economy

Green Finance, becoming a leading carbon trading & services hub, RIE 2025

  • Clients are more likely to get financial support/ more favourable terms for sustainable development.

  • Consultants, contractors can keep an eye out for low carbon technologies funded by RIE2025.

Resilient Future

  • Addressing the urban heat island (UHI) effect

  • be able to produce 30% of our nutritional needs locally by 2030

  • ​Shading devices, cool paint, CFD, environment modelling will become even more prevalent and required.

  • Future mixed-use development may need to provide core & shell suitable for urban farming facilities.

Sustainable Living

  • ​Circular economy

  • 2/3 reduction of net carbon emissions from MOE schools by 2030

  • Recycling infrastructure such as sorting at source, coupled with recycling programmes will be implemented at all building types.

  • If you are working on a MOE project, most likely it is going for the super low energy (SLE) target.

Diagram 8: MND's '80-80-80 by 2030 infographics

Within the 'Energy Reset' pillar, the building sector will contribute based on the 4th Green Building Master plan's '80-80-80 by 2030' goal.

Greening Singapore's GFA means having those constituting buildings certified under the Green Mark scheme. The criteria for achieving super low energy #SLE can be found here.

The World Green Building Council Strategy

The 2020 WGBC Annual Report presented 3 strategic impact areas based on SDGs and climate science recommendations. They are Climate Action (total decarbonisation of the built environment); Health and Wellbeing (delivering healthy, equitable and resilient buildings, communities, cities); Resources and Circularity (supports regeneration of resources and natural systems, provide socio-economic benefits through a thriving circular economy). These strategic areas each target several UN SGDs.

There are several parallels between the WGBC strategy and the Singapore Green Plan. For example, 'Climate Action' can be encompassed by 'Energy Reset', 'Resource & Circularity' share similar objectives as 'Sustainable Living'. 'Health and Wellbeing' can be demonstrated by 'City in Nature'. The Green Plan is broader and has more targets since it extends beyond the built environment.

The United Nations Sustainable Development Goals #SDG

Green Mark 2021 has been crafted with SDGs in mind. The SDGs are a set of 17 integrated and interrelated goals to end poverty, protect the planet and ensure that humanity enjoys peace and prosperity by 2030. It is comprised of 17 goals and 169 targets. Through working to achieve these targets, humanity hopes to (1) end poverty and hunger, (2) protect the planet from degradation, take urgent action on climate change, (3) ensure all human beings can enjoy prosperous and fulfilling lives, (4) foster peaceful, just and inclusive societies and (5) achieve the above with revitalised global partnership for sustainable development.

Diagram 9: Green Mark 2021 sections mapped to UN SDGs
Diagram 9: Green Mark 2021 sections mapped to UN SDGs

In summary, life cycle #Carbon footprint inclusive of operational carbon, expressed in the form of #EnergyEfficiency and #Maintainability, will be the key focus in the coming decade. Health and Wellbeing form another pillar to enhance the functions of buildings and provide social equity. #Resilience acts like insurance policies against climate change while #Intelligence is the support system that enables all other sections.

A holistic view of #GM2021

We are most familiar with GM NRB 2015 as we have been working with it for the past 7 years. We aim to highlight some of the key new initiatives of 2021, followed by an overview of similarities and differences between the two versions. We hope this can allow you to quickly grasp the new GM.

Summary of new initiatives

  1. All projects with GM Certification are expected to achieve > 50% improvement in energy efficiency compared to a 2005 new building. This is in alignment with the 4th Green Building Masterplan whereby 80% of the buildings in Singapore must be greened. We have also departed from the familiar '30% savings = platinum rating' based on GM energy modelling baseline and SS standards. In our opinion, this is a more stringent but welcomed change as engineers no longer need to struggle with 'moving goal post' during GM version and/or SS standard updates.

  2. Energy efficiency is the only prerequisite in GM: 2021, aimed at ensuring projects reduce their operational carbon and utility bills from the reduction in energy consumption. There are 3 pathways to justify energy efficiency status. (1) Energy Use Intensity (EUI), (2) Fixed metrics and (3) Energy modelling demonstrating % savings.

  3. The 5 other sustainability sections shown in diagram 9 can each be scored to a maximum of 15 points. A project scoring 10 points and above for each section qualifies to get a badge representing their exceptional performance in that area.

  4. The modular nature of the sections allows easy individual section updating without having to revise the whole framework.

  5. Energy modelling submissions need to be endorsed by PE (Mech), PE (Elec) and GMAAP. CFD simulations need to be endorsed by GMAAP. Energy audit and Operation System Efficiency (OSE) reports needing to be endorsed by PE(Mech) or registered energy auditors. These requirements reflect a greater emphasis on the accuracy of energy modelling through shared responsibility, promoting integrated design, and accuracy of operating building performance.

  6. GM:2021 is still a work in progress so while it applies to a vast majority of buildings (e.g. high-rise residential, commercial, industrial, institutional etc.), it does not apply to interior fit-out projects (a.k.a. occupant-centric schemes by BCA).

Diagram 10: Green Mark 2021 ratings, what you need for respective certification levels
Diagram 10: Green Mark 2021 ratings, what you need for respective certification levels

To achieve platinum status, a new building will need to achieve more than 60% energy savings compared to a 2005 building and score at least 40 points amongst the 5 sustainability sections. There is no minimum required points for each section.

Green Mark 2015 vs 2021

Criteria from 2015 that remains relevant in 2021 have been brought over but the points allocation has been revised. Some criteria that used to be under one section has been dissected within the new GM 2021 framework.

Diagram 11: Commonalities of GM 2015 and 2021
Diagram 11: Commonalities of GM 2015 and 2021

The 2021 Energy Efficiency (EE) section has almost the same criteria as 'Building Energy Performance' from 2015 with some key differences. Comparison baseline is established as a new building in 2005. #ETTV used to be under Climate Responsive Design and has now been shifted as part of the EE section as well.

Concerning the 3 pathways of EE, each project will have to choose what is most suited for the development and the project team.

In our opinion, Pathway 1 EUI is the most flexible choice. The solutions can be like water flowing around tough rocks of the site and budget constraints, allowing designers to maximise passive design and use strength in one system to complement shortfalls of other systems, always working towards the goal of a lower EUI.

Pathway 2, fixed metrics, is the easiest to execute because of the clear design specifications provided though it might not be cost-effective. The rigid requirement prevents designers and engineers to deploy creative space cooling methodologies and does not reward the project team for passive design.

Pathway 3, energy modelling, is what we are all familiar with. We see it as a battle against the baseline building quantified in the energy modelling guide. In all aspects, such as MEP and facade design, the design building must out-perform the 'competition'. There are some areas for innovation such as allowing for plug load savings and passive design, though some of these have caps that limit the upside potential.

Maintainability shall be left aside for now as it is completely new and deserves an article on its own.

New in GM 2021
Diagram 12: New criteria in 2021
Diagram 12: New criteria in 2021

We notice that there is more focus beyond buildings. Criteria such as 'Mindfulness programs', 'Access to a healthy diet', 'Responsible procurement', 'Tenancy offsets' and 'Data ethics' are soft aspects of any building. As mentioned in previous sections, integration and connectivity are encouraged through criteria such as 'Active mobility', 'Access to Nature' and design for 'Communal Spaces'.

We would like to briefly elaborate on 3 criteria that might be more foreign to the industry. Outdoor thermal comfort, whole-life carbon calculation and implications for the intelligence section.

Outdoor Thermal Comfort

The criteria stated that for 2 points, we need to demonstrate through environmental modelling, taking into account the UHI effect, that the space can achieve either Physiological Equivalent Temperature (PET) of <34 degrees or UTCI of less than 32 degrees. Just what are PET and UTCI?

Aldakheelallah, Abdullah. (2020). A Study to Evaluate Urban Heat Mitigation Design Strategies to Improve Pedestrian’s Thermal Perception in Existing Canyons of Extreme Hot-Arid Cities. The Case of Phoenix, Arizona.

Diagram 13: Ranges of the thermal indexes Predicted Mean Vote (PMV) and PET for different grades of thermal perception by human beings and physiological stress on human beings (Modified after Matzarakis et al., 1999) (Oke et al., 2017).

The table provided a corresponding physiological response description for PET and UTC. Taking the more stringent requirement, UTCI, we can see the equivalent thermal perception of 'slightly warm' or better is required to achieve the 2 points.

The software's calculation is complex, but we can understand it intuitively with the following diagram. Where T-a is the air temperature, T-mrt is the mean radiant temperature, RH is the relative humidity, W-s is the wind speed in metres/second.

There is a 'heat balance' within a standard human body with the conditions seen at the bottom of the diagram (weight of 85 kg, activity level of walking, clothing level of 0.5). In simplified terms, if there is slightly more heat gain than heat loss, that will be 'slightly warm'. There are some things designers cannot control. For example, if the users are doing strenuous exercises then their Internal heat production will be much higher though GM requirement does not call for catering to extreme circumstances. What we can control will be heat gain from radiation through architecture design and sweat evaporation, convection through wind speed.

We believe that the requirements are crafted to encourage architects and MEP to work together. Architectural design and material selection determine opportunities to maximise natural ventilation and minimise heat gain. However, design alone cannot address temperature peaks especially in the era of climate change. This is where good design can be complemented with mechanical systems to address outdoor humidity, wind speed and temperature to achieve thermal comfort. Examples commonly seen around Singapore include misting fans and High Volume Low-Speed fans (HVLS).

Whole-life carbon calculation

Generally speaking, a building's whole-life carbon calculation can be broken down into 2 components. The Static stage - collection and analysis of results from the as-built stage, and the Dynamic stage - consider the operation and maintenance carbon footprint. The static stage can affect the dynamic stage but not the other way round. For example, efficient air conditioning design provides energy (and carbon footprint) savings during the Dynamic (operation) stage as less scope 2 carbon emissions (indirect, owned) is generated. However, no matter what we do during building operations, we cannot change the embodied carbon content of the concrete, steel and glass that was used during the construction stage, neither can we modify the emissions from the cranes and excavators.

This makes the concept design and the use of the digital life cycle (from the intelligence section) extremely important if you are targeting a carbon-neutral project. 'Build digitally' allows the project team to estimate the carbon emissions from the 'static' stage, thereby reducing material wastage, abortive works and optimal work schedule, all of which will reduce carbon footprint. For a summarised considerations for whole-life carbon calculation, please see the diagram below.

Because of the whole-life consideration, the useful lifespan of equipment is important. Other considerations include minimising maintenance or designing for maintainability which can reduce operational carbon footprint.

Intelligence section implications

The intelligence section starts off digital life cycle, common data environment (CDE) and asset information model (AIM), we opined that these are the basic infrastructure needed for buildings of the future to create total digital twins.

What is a digital twin? In simplified terms, a digital twin is a virtual representation of the elements and dynamics of an IoT device that improves the design, the build, and the operations of a product. Elements could refer to components or parts within a machine, or areas within buildings. Dynamics refer to the measurement of generated action.

For example, the elements of an IoT enabled elevator will include a digital log of the lift doors, motor, generator, suspension ropes, counterweight etc. with information such as last service date, and usage rate. The dynamics will be data collected using sensors on door closing speed, motor power consumption, lift vibration movement, number of trips made etc. All information shall be used to create a digital twin of the lift.

The elements and dynamics data collected provide insight when wear and tear deviate from standard cases. Instead of changing parts using a fixed maintenance schedule, the data enables informed and targeted parts replacement, the beginning of predictive maintenance. It is called digital twin because when the physical device 'drifts' from factory test conditions, the digital twin 'drifts' with it, and provide us with valuable insights.

From a design perspective, the intelligence section shows us a future where more areas need to be designed with power outlets and network connection points for the deployment of sensors and/or WiFi communication hubs due to the increasing need for more IoT devices. Equipment specifications need to include digital twin and analytics packages from vendors. thus I am afraid to announce that the subscription model will not be going away. Lastly, MEP performance will be tracked more extensively and accurately than ever. The gap between designed and operational performance may be getting smaller and smaller.

The Takeaway

We hope this article has managed to provide sufficient context for why GM 2021 is needed and aligned to global movements. We have chosen to write about new criteria in GM 2021 that interest us the most which is by no means a comprehensive study of the new framework. We invite you to explore the new framework and throw your questions at us so we can work together to realise sustainable development for Singapore.



In the sequence of appearance

  1. Green Mark 2021 (

  2. IPCC, 2021: Summary for Policymakers. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S. L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu and B. Zhou (eds.)]. Cambridge University Press. In Press.

  3. Average Temperature Anomaly. Morice, C. P., J. J. Kennedy, N. A. Rayner, and P. D. Jones (2012) Quantifying uncertainties in global and regional temperature change using an ensemble of observational estimates: The HadCRUT4 dataset, J. Geophys. Res., 117, D08101, doi:10.1029/2011JD017187.

  4. Berkeley Earth. Global Temperature Report for 2019. Available at:

  5. IPCC, 2021: Summary for Policymakers. In: Climate Change 2021: The Physical Science Basis. Pg. 7.

  6. Annual production-based emissions of carbon dioxide (CO₂), measured in tonnes per year. Global Carbon Project. (2020). Supplemental data of Global Carbon Budget 2020 (Version 1.0) [Data set]. Global Carbon Project.

  7. IPCC, 2021: Summary for Policymakers. In: Climate Change 2021: The Physical Science Basis. Pg. 23.

  8. Climate Action Tracker.

  9. How much is a ton of carbon dioxide? MIT Climate Portal. Kathryn Tso.

  10. Global Greenhouse Gas emissions by sector. Climate Watch, the World Resources Institute (2020)., Hannah Ritchie (2020)

  11. The Singapore Green Plan. (

  12. Singapore Green Building Masterplan (

  13. WorldGBC Annual Report 2020 (

  14. Transforming our world: the 2030 Agenda for Sustainable Development (

  15. Green Mark NRB 2015 (

  16. Aldakheelallah, Abdullah. (2020). A Study to Evaluate Urban Heat Mitigation Design Strategies to Improve Pedestrian’s Thermal Perception in Existing Canyons of Extreme Hot-Arid Cities. The Case of Phoenix, Arizona. 10.13140/RG.2.2.36311.09120.

  17. Whole life carbon assessment for the built environment. (

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