Near-Zero Energy Buildings for Tropical Climates
Malaysia aims to reduce its greenhouse gas emissions by 2030 as well as increase its renewable energy usage. One of the primary energy consumers in the country is school buildings, which are only behind air-conditioners as the top energy consumers. As much of this consumption comes from artificial lighting, daylight exploitation has been suggested as an alternative given Malaysia’s generally sunny tropical climate. Using daylight in place of artificial lighting will lower energy consumption costs and greenhouse gas emissions by a wide margin but school occupants will need to be made aware of its benefits.
Malaysia has a national target to achieve 20% renewable energy capacity mix by 2025, and a global target to reduce 45% of its greenhouse gas (GHG) emissions intensity by 2030 per the Conference of Parties 2021 (COP21) in Paris. However, one roadblock to this goal is the energy efficiency of our educational buildings, with particular concern regarding their usage of artificial lighting. Indeed, school buildings in Malaysia consume 22% of the country’s electricity for lighting purposes and are ranked as the second top energy consumer in the nation after air-conditioning systems (38%).
This consumption ties into the comfort and performance of the students/teachers and the indoor environmental quality (IEQ) of the classrooms. Thus it is vital that we balance this together with energy efficiency (EE) strategies. This can be achieved by adopting daylighting as an energy-efficient-design and well-being approach. This approach is very useful especially given that the tropical climate of Malaysia has a high life cycle cost (LCC) that will strongly benefit from EE improvements as well as daylight that is consistently available from the hours of 8am to 6pm. But there is the issue of increased indoor heating from overexposure of daylighting.
Other contributing factors to the high energy consumption at schools are the usage of internal blinds to minimise/eliminate heat at the cost of less natural daylight filtering, use of air-conditioners and school occupant behaviour with most occupants largely favouring artificial lighting.
Ongoing research conducted by Dr. Norhayati Mahyuddin at the University of Malaya aims to highlight and understand the implications and effects nearly zero-energy building (nZEB) design has on energy consumption specifically within a school environment, and the corresponding influence on the thermal and visual comfort and wellbeing of the occupants. As an advanced low-carbon energy-efficient building solution, nZEB focuses on basic, practical, and viable elements in a sustainable building. The LCC analysis results indicated that investing in nZEB renovations are more cost-effective in the long term compared to a renewable energy investment by minimizing the total cost, and the carbon footprint of the building over its lifetime.
The study is being conducted at Tadika Universiti Malaya (TADIKUM) pre-school with daylight and lighting parameters having been conducted in real-time on-site. Lighting and daylighting as the key factors corresponding to visual comfort have been assessed at the first stage of analysis. Heat reduction is categorised under thermal comfort assessment which is the current and last stage of this ongoing project. These results will be shared with the pre-school principal to consider modifications in the building to exploit more daylight for wellbeing and increasing productivity of the pupils while also decreasing energy consumption. (See Figures 1 and 4.)
The study found that the TADIKUM classroom has the potential to exploit daylight throughout its entire operating hours from 8am to 4:30pm, leading to a significant reduction in energy usage and carbon emissions. Indeed, the results from this research demonstrate that daylight exploitation in Malaysian pre-school classrooms can improve the daily cost and performance of clean energy, up to RM18,858.90 per day (yearly RM3,658,626.6 ) and a reduction in 43,353.80kWh electricity usage and 25,362kg of CO2 emissions. (See Figure 3.)
The key findings of this study will serve as a starting point by the occupants/school boards for moving schools towards nZEB via exploitation of daylight and its integration with artificial light, highlighting the improvements made in classroom EE. We must also consider the interaction between EE and user behaviour and how they influence each other as, more often than not, the occupants are not aware of climate change issues at their finger. Changing the way school occupants behave has the potential to achieve energy savings of between 5-15%.
Figure 1. Daily energy usage, cost, CO2 emissions of the current artificial lighting system in the pre-schools’ classroom(s)
Figure 2. Analysis of visual comfort of classroom
Figure 3. Prospect electricity consumption reduction in transition to nZEB
Associate Professor Dr. Sr Norhayati Mahyuddin
Department of Building Surveying, Faculty of Built Environment
Image by Foundry Co from Pixabay