In half a century, global energy consumption more than doubled from 68,792 terawatt-hours (TWh) to 176,431 TWh. In comparison, Singapore’s energy consumption per capita increased 4.5-fold in the same period, placing her in the top 3 energy consumers in the world per capita.
At first glance, the fact that a small city-state with a population size of 5.64 million could consume close to 8 times more energy per capita than global norms, does not add up. However, when we consider that manufacturing and services are the twin engines of growth in the Singapore economy which consume close to 80% of the total energy, the numbers may not come so much as a surprise.
Similarly, energy consumption in the built environment sector is also trending upwards – the Singapore construction sector saw a 22% Year-on-Year growth in electricity consumption in 2021. Furthermore, buildings count for over 20% of total carbon emissions. The challenge therefore is lowering energy consumption without interrupting nor compromising business and economic growth.
Singapore’s green building journey begun in 2005 with the introduction of the BCA Green Mark, which remains the anchor reference for Green Mark energy savings to date. Since then, the Green Mark certification has undergone numerous reviews, with the latest paradigm shift introduced – the Super Low Energy (SLE) programme. This is the “next wave of Singapore’s green building movement” pushing the envelope of environmental sustainability, with ambitious low energy use targets being set.
The challenge is that buildings in the Southeast Asian tropical climate require cooling year-round as annual average temperatures remain above 32°C, coupled with high humidity and rainfall. Further, with global annual temperatures rising faster and the 10 warmest years on record all occurring in the years since 2010, demand for cooling is heating up. Notwithstanding this, the Green Mark: 2021 (GM:2021), with its calibrated standards, has introduced a minimum of 50% energy savings above 2005 building codes for new buildings, and more than 60% energy savings for the SLE category. This is a daunting challenge for our small, land-scarce island nation.
Our current strategy relies on a combination of passive and active design strategies, featuring smart energy management strategies and the use of renewable energy. With these, an energy efficiency improvement of over 50-60% may be realised. The balance of 40-50% to achieve Net Zero Energy, remains Singapore’s biggest challenge, if carbon offsets are not being considered.
Passive design considerations for SLE buildings include allowing for non-air-conditioned areas within the building (more than 25% of the gross floor area), which requires some clever designs to bring natural air flow through the open areas and at the same time introduce green spaces and natural daylight in the midst of the concrete jungle.
At the same time, the concrete jungle is designed to mimic a lush forest with the addition of plants to towering blocks, taking “greening” literally. Vertical gardens, living green feature walls and urban rooftop farms help improve urban environment by mitigating urban heat island effect and improving air quality. Biophilic designs also improve people’s physiology and mental health through increased connectivity to the natural environment.
Other “age-old” tropical passive designs include a North-South building orientation and the use of overhangs, sunshades or screens to reduce its cooling load. Reducing glazing areas in the sun path and the use of low emissivity, double glazed dark glass with the fins and shades can reduce the Envelope Thermal Transfer Value (ETTV) to 38 W/m2 or less.
Apart from the selection of more energy efficient mechanical and electrical plant and equipment (i.e., Air-Conditioning Total System Efficiency at 0.68 or lesser, use of LED lighting, etc.), harnessing of renewable energy has become more prevalent as a choice of active design. In the Singapore context, solar energy is one of our most promising renewable energy sources, which has led to many existing and new buildings installing photovoltaic panels, reducing reliance on non-renewables. Vertical panels to facades are even being introduced, even with their low efficiency, to harness as much as we can.
The capacity of grid-connected installed solar grew more than 5-fold in as many years from 2016 to the end of the first quarter of 2022. The Singapore Energy Market Authority (EMA) reported that the majority (61.7% or 413.1 megawatt-peak) of solar capacity was accounted for by non-residential private sector buildings. By 2030, Singapore aims to deploy at least 2 gigawatt-peak of solar energy, enough to power 350,000 households for a year. Solar farms on our public housing buildings, water reservoirs and even marine solutions are being considered.
Through the launch of the SLE Challenge in 2018 where developers/ building owners voluntarily commit to achieving at least one SLE project within the next 5 years, the number of Green Mark certified SLE buildings increased from 18 in December 2019 to 65 in just 5 years. More impressively, 40% of which are either Net Zero or Positive Energy buildings.
All of the above, comes with an increase in upfront capital costs. The additional design strategies to achieve an SLE building comes with a cost premium of an estimated 8% over a GM:2021 Platinum building (55% energy savings above 2005 building codes for new buildings), with the bulk of the cost due to the selection of more energy efficient mechanical and electrical plant and equipment. As evident from the growth in SLE buildings in recent years, developers are confident that energy cost savings during the operation will outweigh the upfront investment costs.
At present, green buildings are focused on the reduction of operational carbon. As electricity gets greener, operational carbon savings have become the baseline of green buildings as seen in GM:2021. The industry is just beginning to recognise the carbon impact of the entire construction process – from embodied carbon to emissions from the construction itself. Embodied carbon calculations, recovery of and/or the use of crushed concrete waste and tier-based certified green products and services are key sustainability features in GM:2021 as well.
In the near future, emerging green technologies will push more buildings towards super low energy usage or even zero energy or positive energy emissions. Technology advancements in high performance glass such as smart glass, which allows light into a specific spot in a building at a specific time, as well as alternative low-carbon energy sources look set to transform the future of the built environment industry. We are excited to be part of this transformative journey and through our global knowledge and strength, will be ready for the challenge.
References
Building and Construction Authority of Singapore. (2023, January 31). Green Mark Buildings Directory. Retrieved from SLEB Smart Hub: https://sleb.sg/Building/GreenMarkBuildingsDirectory/
Energy Market Authority. (2023, January 30). Retrieved from Singapore Energy Statistics 2022: https://www.ema.gov.sg/singapore-energy-statistics
Our World in Data. (2023, January 31). Energy Use per Person. Retrieved from Our World in Data: https://ourworldindata.org/grapher/per-capita-energy-use
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