Passive Solar Design vs Passive House Design

When building a dream home in Australia, there’s a lot to consider—flooring, windows, overall layout—but have you thought about energy efficiency? An energy-efficient home isn’t just good for the environment and your health; it also saves you heaps of money in the long run.

There are two key approaches to creating energy-efficient homes: passive solar design and passive house design. Passive solar has been successfully used in Australia for around 40 years, while passive house, a European concept, has only recently made its way here. Both aim to reduce energy consumption, but they take very different approaches towards achieving it.

What is passive solar design?

Passive solar design is all about using natural energy from the sun and the wind to warm or cool an indoor space. Through the simple and cost-effective method of opening and closing doors, there are no mechanical systems in place such as air cons. Rather, it’s a design that offers a healthy environment as well as year-round comfort whilst using little energy.

Solar passive house design dates back to a time when mechanical cooling or heating didn’t exist. Instead, people analysed the sun’s position in the sky and developed design principles around managing their space to match it, so they could maximise solar gain. This method is still used widely today.

For example, home builders could position large glass windows towards the north-facing side of a house to capture the sun's heat as it was rising to warm the home in the morning. Or they could implement concrete floors or walls in regions where it wasn’t as warm all year long to help keep buildings comfortable on cloudy days. If a breeze constantly came from the same direction, home builders could select window openings that face the cool summer breeze to help concentrate on cross-flow ventilation through the home.

Passive solar design relies on seven key factors: orientation, zoning, thermal mass, shading, insulation, ventilation, and glazing. All must be considered to achieve the top level of comfort. With rising energy costs and a greater focus on sustainability, passive solar design is a great option for modern homeowners.

What affects a passive solar design?

There are four key factors that affect a solar passive design:

• The allowable orientation of the building

• The amount of winter sun hitting the glass

• Insulated building materials

• The behaviour of the occupants and their participation

As mentioned earlier, materials like cement help retain heat, and north-facing windows increase the chances of naturally warming a space. However, an occupant's behaviour also makes a huge difference. During hot days, occupants can close windows and blinds to prevent excess heat buildup and then reopen them in the evening when temperatures drop, allowing for natural cooling. This type of help can greatly influence the effectiveness of passive solar design.

With passive solar design, you don’t really need to control the temperature inside because it all happens organically. This method costs less upfront than a passive house design and has a more positive environmental impact since it uses fewer building materials.

What is passive house design?

Through the use of energy-efficient tools, a passive house design uses a methodical, precisely calculated method to create a low-energy home. In contrast with passive solar, passive house design attempts to offer a certainty of temperature, regardless of the sun. This style offers year-round comfort anywhere in the world, no matter the weather. If heat energy loss happens through windows, it will be replaced by the combination of electricity and the sun. It guarantees results.

As mentioned, this design focuses on actual, measured values. The goal of a passive house design is to achieve an indoor comfort temperature of 20-25 C with no more than 10% of the year exceeding 25 C. Why? Because a home within 20-25 C is the ideal, comfort temperature, so maintaining it year-round would be enjoyable for most occupants.

To achieve a successful passive house design, these 5 aspects must be considered: orientation, appropriate insulation, airtightness, high-performance windows, and balanced ventilation with heat recovery.

What affects a passive house design?

In a passive house design, the space must be near-airtight with good insulation to prevent heat loss through drafts. You wouldn't want to be paying for heat just to lose it. Therefore, the better designed your space is, the less energy wasted. This method also minimises thermal bridges and MVHR systems that are often used to bring fresh air into a building and remove moisture. Think of it as a more strategic way of heating and cooling your home without breaking the bank. Because if you can create a home that stays consistently comfortable all year round, without racking up high energy bills, it can lead to significant energy savings over time.

What is the key difference between the two designs?

When we compare the two designs, a passive house is more rigid and has more regulations than passive solar design.

Below are the key needs of a passive house:

• Heating demand max 15kWh/m2/yr OR Heating Load 10W/m2

• Cooling demand max 15kWh/m2/yr OR Cooling Load 10W/m2

• Air tightness of 0.6 air changes per hour at 50Pa (ACH50) (Air tightness must be a guarantee because it must be tested before completion and certification)

A passive building design has more strict requirements for airtightness, whereas passive solar homes can be airtight, but typically rely more on natural ventilation for fresh air. However, this approach only works if windows are opened regularly by occupants to allow sufficient airflow.

Which design should you choose?

Both designs can deliver affordable, long-term savings and enjoyable climates. At the end of the day, it’s up to you and your preferences.

Considering your climate and location in relation to the sun is a great starting point for choosing the right design. Passive house plans are more adaptable to different locations, providing a consistent, comfortable indoor environment regardless of where you live. You can pay for a lower amount of energy but still have a high-quality level of living. However, it's a bigger investment upfront and requires you to fulfil stricter criteria.

On the other hand, passive solar relies heavily on proper home orientation—if it’s not positioned correctly, maintaining comfort through natural heating and cooling can be more challenging. But when positioned properly, with the best windows and doors in the industry, the natural results speak for themselves, offering warmth in winter, cooling in summer, and reduced reliance on artificial heating or cooling. Both approaches have their benefits, so the best choice comes down to what suits your lifestyle, budget, and location.

With that in mind, Miglas’ trademarked AluClad windows offer the best of both worlds in both designs—combining timber’s insulation with aluminium’s durability for a low-maintenance, energy-efficient solution. Designed to withstand the harsh Australian climate, these double-glazed systems provide year-round comfort while allowing full architectural flexibility in style, size, and colour.

Ready to create your forever home?

If you’re about to make big decisions in building your home, it’s worth considering how your design choices will impact comfort, energy efficiency, and long-term costs. The right windows and materials can make all the difference in maximising your home's performance.

If you’re looking to connect with a top window manufacturer in the Melbourne region, contact our team at Miglas for details on sustainable and effective windows and doors. We have many experts here ready to help you find the right product, like the Aluclad frames, for your future home projects.

Chat with us today.