What are Passive Cooling Strategies?
Passive cooling strategies reduce dependence on mechanical technologies (such as air conditioning) by utilizing design elements, and nature-based solutions to improve indoor thermal comfort, awhile concurrently lowering energy consumption and greenhouse gas (GHG) emissions.
Strategic orientation and placement of the building
Aligning a structure to take advantage of prevailing winds and shade patterns can significantly reduce heat gain. For example, orienting a building to maximize northern and southern exposures while minimizing eastern and western exposures can limit direct sunlight penetration.
Materials and Technologies
Insulating materials, especially locally sourced, provide climate-specific solutions, lowering energy demand, embodied carbon, and environmental impacts. Additionally, employing reflective and light-colored materials for roofs and walls minimize heat retention.
Ventilation
Natural ventilation strategies, such as cross-ventilation and stack ventilation, facilitate air movement through the building, expelling warm air and drawing in cooler air. Cross-ventilation involves strategically placed windows and vents to create airflow paths, promoting the exchange of indoor and outdoor air.
Shading
Overhangs, louvers, shutters and vegetation can protect the building from direct solar gain. Vegetation, including green roofs and facades, not only provides shade but is also contributes to evaporative cooling, mitigating the urban heat island effect around the building.
Growing Cooling Demand in an Era of Escalating Heat
- Southeast Asia is undergoing rapid urbanization, economic growth, and population expansion. Without intervention, these trends, coupled with a warming climate, will exponentially increase energy consumption for comfort cooling and related emissions.
- According to the 2022 Cambodia National Cooling Action Plan, demand for space cooling is projected to double from 2020 to 2040, in Cambodia.
- Buildings currently account for one-third of the country’s total final energy consumption, with space cooling representing 45%, the largest share, of electricity usage due to Cambodia’s hot and humid climate.
- Taking action to reduce the reliance on mechanical cooling is crucial to mitigate emissions and manage the strain on the energy grid caused by the growing use of cooling appliances.
Global Cooling Potential
- Addressing cooling involves tackling a range of interconnected challenges, such as mitigating climate change through reducing cooling-related greenhouse gas emissions, adapting to increasing extreme heat, promoting equity and universal access to cooling, and advancing the Sustainable Development Goals (SDGs).
- As global temperatures rise, passive cooling design offers a viable solution for enhancing thermal comfort while mitigating environmental impact. These strategies are flexible and tailored to local climates. Implementing passive cooling design in new building projects can reduce cooling loads by 30 to 40% (Al-Tamimi 2022). Retrofitting existing buildings can also reduce cooling loads by 10 to 20% (Hondeborg et al. 2023).
ESTIMATED PROJECT IMPACT
Passive cooling is considered a priority by building sector stakeholders, and a preferred option to reduce reliance on active cooling system.
2% of the existing building stock (residential and commercial) is retrofitted and 20% of new buildings utilize passive cooling strategies.
Achieve energy savings of 10% to 20% or more by integrating passive cooling in retrofits and new construction, significantly outperforming the energy efficiency of conventional buildings of similar standards.
New building energy regulations incorporate specific performance requirements for cool roofs and building envelopes, driving increased adoption of these energy-efficient solutions.
Passive cooling and adopted practices are adequately accounted and monitored in the GHG inventory and contribute to the achievement of the NDC commitments.
Based on estimates, the project could contribute cumulatively to 0.5 MtCO2eq reduction by 2030.