Global trends are forging ahead but challenges remain for Asian cities in hot-humid climates
The recent IPCC report warns that we have 12 years to limit temperature rises to under 1.5 degree Celsius to prevent a climate change catastrophe, and calls for urgent and unprecedented changes for us to reach the target. Following COP21 at the end of 2015, the World Green Building Council (WorldGBC) issued a campaign to rise to the challenge: by 2030, all new buildings to be net zero carbon, and by 2050, all buildings must be at net zero carbon. In our definition of net zero carbon buildings, they are highly energy efficient buildings with remaining energy demand coming from a combination of on-site and off-site renewable generation sources and, where appropriate, offsets. We have focused on operational carbon to start with (as end-energy use makes up 28% of carbon emissions attributed to the building sector, out of a total of 39%), but as building performance improves, embodied carbon will be increasingly important as well.
Over the last two years since the launch of our global project Advancing Net Zero, we have mobilized our Green Building Councils in 17 countries, covering nearly 50% of global population, to start their journeys towards decarbonising the building sector, in education and training, certification and policy. However, none of these countries are in the hot-humid climatic zone and have an issue with high density. In many Asian cities, carbon footprint and energy consumption are significant: Asian cities are bursting at the seams, and as people move into cities for work, air conditioning is required for comfort and productivity. This creates urban heat island effect from hot exhaust air spewing from buildings, which in turn escalates the demand for more cooling. Additionally, the high heat and cloud cover also reduces the efficacy of solar panels. How does one achieve net zero carbon in such a challenging context of hot, humid and high-density?
Despite the technical challenges, several zero energy demonstration projects have sprung up in the region over the last decade. With thoughtful design, environmentally-conscious behaviour from occupiers and renewable energy generated on-site, it is possible for low rise buildings. But as the majority of buildings in Asian cities are high rise, these examples are often dismissed as irrelevant and not applicable to the Asian city context.
The tide is changing with ASEAN countries taking leadership
Since the launch of WorldGBC’s Advancing Net Zero program, we have observed a sea change in attitudes towards zero energy buildings (ZEBs). In Singapore, at the recent International Green Building Conference, the Building Construction Authority launched the Super Low Energy certification, where high rise buildings are challenged to deliver energy improvement of 60% above the 2005 building code, which translates to achieve a Energy Use Intensity (EUI) of 25 kWh/m2/year for school, 100 kWh/m2/year for office, and 160 kWh/m2/year for hotel and retail. We saw many of our close partners such as Keppel and CDL pledge their commitment to reduce their energy consumption drastically. In addition, there is an alternate zero energy pathway where off-site renewables are allowed, provided EUI requirements are achieved first.
In Malaysia, they have started the conversation through the recently concluded conference on Towards Net Zero Energy Buildings in Kuala Lumpur and, one of the recommendations from Sustainable Energy Development Authority Malaysia (SEDA) was to adopt the Japanese model of ZEB-ready, nearly-ZEB and ZEB which looks at a stepwise approach for approaching zero energy and ultimately, zero carbon. While both countries have adopted an energy-centric approach, as corporates are increasingly aware of their overall sustainability impact due to developments such as the Taskforce of Climate-related Financial Disclosures (TCFD) and Investor Agenda, they would be thinking about carbon as the ultimate metric to track, across their supply chain, production and operations.
How best should we start?
Taking a leaf from the above, we could adopt a two-prong approach.
Firstly, define what is a good stretch goal in terms of energy demand reduction and be specific about the metric, particularly KWh/m2/year. Typically, 30-50% improvement from current baseline year are considered a good stretch.
In fact, there are many proven and low cost technologies that can deliver substantially more energy savings such as:
- LED and smart lighting: up to 80% of energy savings
- Install occupancy sensors in tandem with when the air conditioning is in operation: 10 to 15% energy savings
- Using hybrid cooling methods: assisted ventilation such as ceiling fans in tandem with traditional air-conditioning: 10 to 15% energy savings
- Either install solar or adopt a solar leasing model to reduce capital costs
Reducing energy demand of the buildings by using currently available and established technologies and techniques can significantly improve the viability for on-site solar generation, future proofing developments for cost effective procurement of off site renewable energy generation solutions, grid decarbonisation and/or offsets.
Secondly, it would be useful, particularly for policy makers and NGOs, to segment building based on typologies and height and through that, identify the low hanging fruit which can then be shaped into industry level initiatives that can move the market. For instance:
- Schools and university campuses (generally low rise)
- Government / public buildings (generally low to mid rise)
- Commercial buildings (generally high rise)
We met with Prescott Gaylord, Sustainability Manager at the Singapore American School (SAS) recently to understand how he has quantified his energy saving experiments around the campus. One of the experiments would naturally involve Air Conditioning and Mechanical Ventilation (ACMV) systems, given that it consumes typically 40-60% of total energy consumption in buildings.
Initially, occupancy sensors were installed in one suite of rooms where there were air conditioned offices and student lounge space, and in tandem, the variable air volume boxes of the air conditioning system would close if no one was in the room or space. In addition, the standard Alternating Current (AC) motors in the old Air Handling Unit (AHU) and the outside fresh Air Handling Unit was retrofitted with a Direct Current (DC) motor called an Electronically Commutated Motor (ECM). This further cut the fan energy in the AHUs and allowed the fans to ramp down dynamically to take advantage of savings when spaces were unoccupied.
With the help of air side monitoring software, SAS measured the energy savings from these two changes at 73% from the pre-retrofit levels. They believe roughly half of that saving comes from the addition of sensors and half from the fan retrofit. The extra cost of the upgrades compared to their traditional planned renovation was minimal – 5% to 15% of the ACMV budget. With 73% savings, the payback was less than one year. Prescott notes that no new innovative technologies were used and both interventions included off-the-shelf technologies that are readily available in Singapore; and if applied to the whole campus, will place the campus at near Super Low Energy certification levels.
So why don’t we do it if energy efficiency and super low energy is technically feasible?
The question remains, why don’t we do it if seemingly aggressive energy efficiency targets are within reach, and technology has existed for the last two decades? Just as it is hard for people to eat their seven a day or exercise for 300 minutes a week, despite the advances in fitbit and tracking devices, it is similarly hard for buildings to be efficient as life gets in the way, and there’s always something more important to do. But every minute we waste, we are likely wasting unnecessary use and cost of energy and therefore fossil fuels – putting us dangerously close to our global climate limits.
One possible way to reduce the barriers of implementing energy conservation measures is the concept of “servitisation”, where the service is in the hands of an expert and, cooled air and lighting are sold as a service. Once people move to a pay-per-use model, perhaps they will feel the direct and immediate cost savings of energy efficient behaviours. This is not a new concept – we have music-as-a-service through Spotify, transport-as-a-service through Uber, Grab and Lyft, and entertainment-as-a-service through Netflix. The subscription-based model is prevalent in our daily lives, and if the building industry adopts some of these alternative business models, perhaps we can move towards sustainability-as-a-service and truly enable the reality of net zero carbon buildings by 2030.
Joelle Chen is the outgoing Head of WorldGBC’s Asia Pacific Network; Victoria Burrows is Head of WorldGBC’s Advancing Net Zero program.
This blog includes contributions from Yann Grynberg, Program Director, Sustainable Building Technologies, Energy Research Institute at Nanyang Technological University and Prescott Gaylord, Sustainability Manager, Singapore American School.