Wondering how to design a home that stays comfortable across the seasons without relying on air conditioning or heating?

Discover how orientation, breezes, shading, thermal mass and the building envelope work as one integrated system to naturally heat and cool your home.

Learn what to ask your designer or architect so passive performance is actually built into your project, not just hoped for.

Listen to the episode now.

Hello! This is Episode 403, and Way #3 in the ‘44 Ways to Create Your Sustainable Home’ series here on the podcast.

Over the last two episodes (Episode 401 and Episode 402), we’ve discussed designing for your site’s orientation, and considering how your home is positioned to work with the movement of the sun and prevailing breezes. And how your home is designed to maximise natural ventilation, whilst protecting you from harsher wind events on your site.

In this Episode, those two design considerations come together into something larger.

This is where passive solar design becomes a whole-of-home strategy. Where orientation, breezes, shading, thermal mass, and the building envelope work, not as separate decisions, but as an integrated system, designed to keep your home comfortable across the seasons without relying on mechanical or artificial heating and cooling.

Put simply, passive solar design is the practice of setting up the design of a building, in its orientation, its form, its shading, and its construction, to assist with maintaining comfortable indoor temperatures throughout the year, without relying on mechanical and artificial systems. Instead, it optimises the natural assets of the site, especially the sun and its movement.

This draws on what we’ve covered in Ways #1 and #2, and adds two more essential concepts: thermal mass and the building envelope.

When these elements are considered together from the beginning, the result is a home that is more comfortable to live in, less expensive to run, and more genuinely sustainable overall.

In winter, in the southern hemisphere, the sun moves in a low arc through the northern sky. Well-positioned north-facing windows allow that low-angle sun to reach into the home, warming the internal surfaces and air. 

Materials with thermal mass, such as concrete floors, brick walls and stone finishes, absorb that direct winter sunlight and warmth through the day, and release it slowly through the evening and overnight.

In summer, the situation reverses. The sun is high in the sky, and in a lot of climates, its direct heat is not welcome in the home. 

Well-designed eaves or window hoods above north-facing windows block the high-angle summer sun, while vertical shading on west-facing glazing helps protect the interior from harsh afternoon sun. In the evening, operable windows can be opened so prevailing breezes flush accumulated heat from the home.

Thermal mass usually works best where there is a meaningful swing between daytime and night-time temperatures across the seasons. In hot and humid climates with little day-night temperature difference, it is far less effective.

Your local climate is the most significant driver of which passive design strategies deserve the most emphasis in your project. We’ll go into more depth on that in the next episode, but in the meantime, this episode walks you through how passive heating and cooling can work as a system across different climates, and how to approach mechanical heating and cooling intentionally where it’s still appropriate.

In this Episode, we cover:

• What passive solar design really is, in plain language
• How orientation, breezes, shading, thermal mass and the building envelope work together as a system
• The role of thermal mass, how it stabilises indoor temperatures, and where it works (and where it doesn’t)
• How passive design adapts across hot and humid, hot and dry, temperate, and cool to cold climates
• When mechanical heating and cooling is still appropriate, and how to right-size it based on a home’s passive performance
• Why I consistently advocate for all-electric homes, and the case against gas as a fuel source for new and renovated homes
• The questions to ask your design team so passive performance is actually built in, not just hoped for

Plus a whole lot more.

LISTEN TO THE EPISODE NOW.

RESOURCES

Your Home (Australian Government resource) >>> https://www.yourhome.gov.au/ 

ASHRAE Weather Data Centre (National information) >>> https://www.ashrae.org/technical-resources/bookstore/weather-data-center 

NatHERS Climate Zones >>> https://www.nathers.gov.au/ 

’44 Ways to Create a Sustainable Home’ e-guide >>> https://undercoverarchitect.com/ways 

Access the support and guidance you need to be confident and empowered when renovating and building your family home inside my signature online program, HOME METHOD >>> https://undercoverarchitect.com/courses/the-home-method/

Learn more about how to interview and select the right builder with the Choose Your  Builder mini-course >>> https://undercoverarchitect.com/courses/choose-your-builder