Why Passive Design is the way to go?
The term ‘carbon zero’ applies to buildings that use 100% renewable energy sources on site to generate energy for their operation, so that over a year the net amount of energy generated on site equals the net amount of energy required by the building users.
A building is a shelter which protects us from the environment, ensuring it remains thermally comfortable with minimal or no use of artificial heating or cooling, but as the climate changes to extreme weather conditions some buildings are not able to adjust to these needs. This is because, temperatures are increasing, sea levels are rising and extremes in the weather are more likely to happen in some areas.
Applying passive design is designing a building according to climate requirements to ensure the occupants remain thermally comfortable with minimal or no use of artificial heating or cooling in the climate where it is located. Passive design principles works with the climate, not against it.
Applying passive design principles and smart use of materials, it’s possible to lower construction costs, running costs and increase building thermal comfort. Thermal comfort is a state of mind and it’s subjective to each individual who express satisfaction when they can adjust the thermal environment to their needs. In cold weather the body releases heat, therefore the building should be airtight, and in hot weather the body does not release heat but sweats to cool down the body, therefore airflow is required to evaporate the sweat and increase comfort.
Passive Design principles:
Solar Gain: The sun’s energy is used to create internal comfort in winter but will need solar protection in summer to shade the exposed facades.
Benefits: reduces energy costs, improves thermal comfort and performance of the building, and is a good source on site to generate renewable energy.
Passive Cooling: passive elements are designed to contribute to natural ventilation including cooling strategies to prevent the building from overheating by blocking solar gains in summer with external shades and louvers.
Thermal Mass: use of materials with high thermal mass to absorb, store, and later release heat during winter nights, but should be located where the sun has little impact during summer and facing wind flow to cool down the internal areas.
Benefits: reduces energy costs, improves thermal comfort and performance of the building and moderates temperature fluctuations.
Insulation: is a crucial principle of passive design, thermal bridging and air leakage throughout external and internal spaces are to be avoided. This can happen through the structure when it is exposed internally and other building elements.
Benefits: reduces energy costs, insulation costs (it pays itself in six years), reduces greenhouse gas emissions, acoustic properties and eliminates condensation.
Airtightness: is the control of airflow within a building without any unexpected leakage of hot air in winter and vice versa in summer.
Benefits: reduced energy costs, improves thermal comfort and performance of the building.
Conclusion:
Passive Design is an approach to design buildings minimizing energy consumption and reducing use of active mechanical systems, maintaining occupants thermal comfort at all times. Some of the benefits are construction costs savings and running costs of the building during its lifetime, as a result the passive designed building will be Carbon Zero.
Passive design elements to consider when designing a building:
Orientation
Building shape and type
Buffer areas
Planning
Daylighting
Windows design
Wind orientation
Natural ventilation
External shading elements
Optimizing the use of recycling materials where it is possible.
