Shaping Melbourne's Tomorrow: The Art of Passive House Design
In Melbourne, where sustainable construction practices are gaining momentum, Passive House design principles are becoming increasingly prominent. There are a few key considerations for Passive House architects that need to be taken into account when designing a home. Passive House design represents a transformative approach to building construction that equips us with the tools to master the elements. It allows us to seamlessly control moisture, thermal transfer, airflow, and sunlight, forging the path toward the creation of buildings that are not just efficient but truly exceptional. So, whilst we usually stay in our lane and talk about building, we thought we would get stuck into a few key things that need to be considered in the design phase.
Daylight and Solar Gain:
Window Placement and Size: Maximise the number and size of windows on the northern side of the house. North-facing windows receive ample sunlight during the winter months, which can help passively heat the interior spaces. This orientation allows for the effective use of solar energy for heating while minimising solar heat gain in the summer due to the high angle of the sun..
Glazing Selection: Passive Houses often use high-performance, triple-glazed windows with a low solar heat gain coefficient (SHGC). This allows natural light to enter while minimising excessive solar heat gain, particularly during the summer months.
Moisture Management:
In their efforts to bolster building longevity, Passive House designers meticulously assess how heat and moisture function within structures located in particular climatic conditions. The whole idea of moisture management is to prevent the infiltration of bulk water (rain) and deal with/stop condensation that could potentially harm building components.
Vapour Control Layers: Passive House design incorporates vapour control layers to manage moisture. These layers are strategically placed to prevent warm, moist indoor air from reaching cold surfaces where condensation can occur. Proper selection and installation of these layers are crucial.
Proper Ventilation: Passive Houses rely on balanced mechanical ventilation systems with heat recovery (MVHR). These systems not only provide fresh air but also help control indoor humidity levels effectively. By exchanging heat between incoming and outgoing air, MVHR systems minimise moisture buildup.
Local Climate: The local climate zone in which the building is situated also plays a significant role in determining heat and moisture dynamics. Passive House designers rely on extensive data of previous examples and proven assembly solutions to navigate these variables.
Shading:
External Shading: Passive House design often includes external shading elements like overhangs, awnings, or louvers. These elements are strategically designed to block direct summer sunlight while allowing low-angle winter sun to penetrate the building. They reduce the need for mechanical cooling during hot weather.
Internal Shading: Internal shading solutions like blinds, curtains, or shades provide flexibility in controlling light and heat gain. Automated shading systems can adjust based on the time of day and season, optimising comfort and energy efficiency.
Orientation:
Optimal Building Orientation: Passive Houses are typically oriented with the long axis along an east-west axis to maximise passive solar heat gain. This allows for more south-facing windows, which capture the sun's energy in colder months while minimising heat gain in the summer.
Minimise West Exposure: Western sun exposure can lead to overheating in the morning and late afternoon. Minimising the number and size of windows on these sides of the building can help control heat gain and maintain comfort.
Form:
Compact Building Shape: Passive House designs favour a compact building shape with a minimal surface area relative to the interior volume. This compact form reduces heat loss through the building envelope, making it easier to achieve the necessary levels of insulation and airtightness.
Airtight Construction: The form and shape of the building play a role in maintaining a high level of airtightness, a key Passive House principle. Minimising penetrations through the envelope and ensuring proper sealing at joints and transitions are essential to maintaining an airtight building.
Heat Transfer: We strategically orient buildings to harness solar energy efficiently, considering climate and building type. Simplicity in building form is crucial for achieving Passive House standards, as it minimises thermal bridges and reduces insulation needs associated with complex designs.
By carefully considering and integrating these design principles, Passive House builders can create high-performance buildings that optimise daylight and solar gain, effectively manage moisture, provide shading as needed, make the most of building orientation, and maintain a form that aligns with Passive House principles, resulting in comfortable, energy-efficient, and resilient structures.
Pairing yourself with a Passive House architect is essential to achieve the greatest result. There are plenty of awesome ones we have worked with a number of them looking to further develop their name in the space.