Reaching for the Stars

In mid-2025 the Nationwide House Energy Rating Scheme (NatHERS) will be expanded to include existing homes.  Leading up to this we will be exploring ways to achieve, and exceed, 7-stars and a compliant whole-of-home rating for new homes and major extensions.

As of May 2024, we are required to design homes that achieve 7-stars and a whole-of-home rating of not less than 60.  The star rating relates to the thermal performance of the project and how effectively a home maintains comfortable temperatures.

To achieve 7-stars, we focus on several integrated design strategies:

1. Orientation & Passive Design

• Maximize northern exposure allows lower winter summer sun to heat the project and allows for the ability to effectively shade the higher summer sun.
• Carefully designed east/west-facing windows: To reduces unwanted heat gains from the summer sun in the morning and afternoon we consider how to control the entry of sunlight and extent of glazing on the east and western facades.
• Shading: Being able to shade the building and windows reduces the heat load on the project.  Effectively designed eaves, awnings, and pergolas can block summer sun while allowing winter sunlight in.

2. Insulation

• Ceiling/Roof insulation: We design in sufficient space in the roof to use R5.0 or higher insulation that can be up to 300mm thick and considering penetrations of services.
• Wall insulation: We often use 140mm thick studwork to be able to achieve a higher performance of wall insulation of R2.7 and consider what services and other building elements will impact on the continuity of the insulation.
• Underfloor insulation: Insulating beneath suspended floors or beneath the slab significantly improves the perceived comfort of a residence.

3. Double or Triple Glazed Windows

• Use Low-E coated glass: Larger expanses of glass to enhance the connection with the outdoors requires a high-performance glazing to achieve the necessary energy performance.  This allows us to reduce the heat loss in winter and heat gain in summer. For our Passive House projects, we study in detail the thermal bridging and glazing performance of the specified window systems.
• Install  thermally broken frames: In our projects in Central Victoria, we recommend using thermally broken frames. This reduces heat transfer through window frames on cool nights and hot summer days.
• Ensure tight seals: During construction we work closely with the contractor to minimizes air leakage around windows and doors and consider our detailing of these elements to improve buildability.

4. Airtightness & Draught Sealing

• High level of airtightness: The Passive House standard is predicated on a high level of airtightness. Sealing gaps around doors, windows, and vents to prevent heat loss and taping and detailing building wraps are essential to ensuring a high degree of airtightness.
• Heat Recovery (HRV): Due to the higher degree of airtightness that is being achieved in the construction of our projects we are increasingly exploring mechanical ventilation with heat recovery (HRV) to circulate fresh air without energy loss and to assist in maintaining a more consistent internal temperature.

5. Thermal Mass for Heat Storage

• Concrete, brick, or stone:  We consider where we can place thermal mass in our projects to moderate the internal temperature of our projects.  At the Quarry House and Chewton House the concrete floor slabs and carefully placed internal brickwork provide thermal mass to absorb heat during the day and release it at night.
• Thermal Mass: This thermal mass is located inside the insulated envelope so it effectively contributes to the thermal performance of the interior.  Allowing the sun to warm the surface during the day and release this heat overnight as the interior cools.

6. Energy-Efficient Heating & Cooling

• We specify energy efficient heating and cooling including heat pumps for heating and cooling.
• To maintain air movement and reduce the reliance on air conditioning we design in ceiling fans.  
• We design in zoned heating and cooling zones to minimize ducted heating/cooling losses by using zoning systems.

7. Solar Panels & Hot Water Systems

• A solar PV system offsets energy use and provides opportunities to use energy throughout the day when energy is being generated by the solar system.
• Use solar hot water or an efficient heat pump water heater.  The orientation, size, and constraints of a site can influence the choice of the most suitable system.

8. LED Lighting & Smart Design

• LED  Lights: LED technology is constantly developing.  We consider LED lights, sensors in lower-use, and a mix of task and ambient lighting to reduce the reliance and energy usage of lighting.
• Skylights can to reduce daytime lighting needs.  At the Quarry House, skylights were used to allow northern light to enter into the kitchen area due to the east-west orientation of the site and building to the northern boundary due to the site constraints.

9. Sustainable Landscaping

• Deciduous  trees provide summer shade and winter sunlight.  Trees can significantly cool the micro-climate around a project and provide habitat for native birds and insects.
• Drought-resistant plants and permeable paving contribute to reducing the heat island effects and can reduce the water demand of the landscaped areas in and around our projects.

Using FirstRate 5 to explore these design elements and assess our projects during the design process allows for the optimization of these aspects of a design and compliance with the requirements of the National Construction Code.  

‍