- Carmel Homes
Are Passive Houses Expensive?
Updated: Dec 2, 2022
There are many reasons homeowners are increasingly looking to adopt passive house principles in their new home designs. Some are conscious of their carbon footprint and want to reduce the environmental impact of their daily life. Others are concerned about their family’s health and are drawn to the higher air quality passive houses offer.
There are also those who are interested in passive house design for purely economic reasons. Since their earliest days, passive houses have been promoted for their limited need for heating and cooling. And, as the cost of these services continues to increase, so does the desire to reduce reliance on them.
But heating costs are not the only ones to be considered when working out how expensive a property will be. From the price of construction to the need for ongoing maintenance, several important factors contribute to a home’s total cost. Which begs the question – all things being considered, how expensive is a passive house?
Here we attempt to answer this question by looking at both the building and running costs of a passive house. We also explore the factors that impact the price of a passive home and ways to bring down your build costs.
Put simply, passive houses are super-efficient structures that are carefully designed to maintain a highly consistent internal climate. Through the use of specialised design and build techniques, they limit the loss of heat energy and tightly control airflow. Specifically, passive house designs focus on five key elements:
Thermal bridges: This term is used to describe weak spots in the insulation of a space (e.g. windows, ceiling junctions, and balconies). As these are the spots the most heat energy will be lost, they need to be identified and remediated. This is usually done by using specialised products to increase overall thermal protection.
Insulation: While all new houses should feature some form of insulation, passive houses take this a step further. To achieve the level of thermal protection required, higher performance products are used, generally in greater volumes. They are also installed consistently throughout the structure, including underneath flooring, to minimise the presence of thermal bridges.
Double glazing: In Australia, windows are widely recognised as being the biggest thermal bridges in most homes. This is because thin, single-glazed windows are common, and these provide minimal thermal protection. Acknowledging this, passive home designs use special thermally broken double-glazed windows to minimise the potential for heat loss.
Airtightness: While airflow helps keep an internal space feeling healthy and fresh, it also leads to the loss of heat energy. As such, passive houses are designed to tightly control airflow and minimise heat transfer. Generally, a specialised approach is required at both the design and build stages to achieve the desired airtightness.
Ventilation: A specialised system is used to provide a constant stream of fresh air into the airtight internal space. This will feature a heat recovery mechanism, which captures heat from outgoing air and transfers it to the incoming air. It will also have a filtration system that helps manage and maintain air quality within the home.
READ MORE on the 5 Principles of Passive House Design
The key characteristics of passive houses are set out in the Passive House (or PassivHaus) Standard. This document was created to promote the benefits and maintain the quality of passive house design. It also sets out the criteria properties are measured against when seeking passive house certification.
READ MORE on What is a passive house?
How much does a passive house cost to build?
As you would likely expect, because of the specialist products required, passive houses are not the cheapest building option. That being said, the exact cost of construction will vary greatly, depending on things like:
The size of the home: As with any other type of house, the larger a passive house, the more construction is likely to cost. This is because more materials are required to adequately enclose and insulate the space. Important fixtures, like the ventilation system, may also need to be upgraded to deal with the larger building footprint.
The location and condition of your site: If your site is remote or difficult to access, the cost of getting materials to the site will likely be higher. Non-standard site conditions, like an unusual block shape or significant slope, may also require additional design and build works. And, if there is an existing structure, you may need to factor in knockdown and rebuild costs (demolition, remediation works, etc.).
Your preferred design style: Certain architectural styles, like modern home designs, are more suited to being passive houses than others, like French Provincial homes. This is because they can easily be tweaked to meet the principles, and specialised products are produced in these styles. That being said, products like passive house compliant windows are increasingly being produced to suit French Provincial homes, etc.
Your desired quality of finish: As with any other new build, passive houses can be finished to a range of standards, from basic to luxury. And the higher the quality of the fixtures and finishes, the higher the total build cost.
Taking all the above into account, it is difficult to say conclusively how much more a passive house costs to build. For example, some experts say build costs will be 3% - 5% higher than comparable projects with a custom home builder. Others say you should expect to pay approximately twice as much as you would for a similarly sized volume build.
It is important to note here that, as their popularity continues to grow, passive houses are becoming increasingly more affordable. This is because the specialised products required are being produced in greater quantities and a wider range of styles. There are also more designers and builders who have experience working with passive house materials and concepts.
There are also several easy ways to reduce the cost of a passive house build:
Focus on the structure: If you are working with a limited budget, you should prioritise the structural components of the build. While this may mean choosing more modest fixtures and fittings, it should provide all the benefits of building a passive house. And you can always upgrade the fixtures and fittings in the future when you have the money to do so.
Opt for a more modern home design: Modern homes are known for their minimalism and efficient use of space, which aligns well with passive house design principles. As such, if you do not have a specific design style in mind, going modern should make your build easier. Specialist passive house products, like windows and doors, are also usually made to suit a more modern home design.
Remediate existing structures: It is now possible to upgrade an existing home to meet the requirements set out in the Passive House Standard. As such, if your site already has a structure on it, you do not necessarily need to knockdown and rebuild. In fact, upgrading it will likely be the most cost-effective way to realise the benefits of a passive house.
Forgo certification: While there are benefits to getting your passive house certified (e.g. increased resale value), there is a cost associated. Acknowledging this, many of the homeowners who choose to build a passive home do not seek formal certification. This generally means a saving of several thousand dollars and does not impact the performance of the property.
How much does a passive house cost to run?
The big selling point of a passive home is that it requires minimal heating and cooling and is extremely energy efficient. In fact, studies show that a passive house uses as much as 90% less energy than a standard home. Given the ever increasing cost of utilities, this represents a significant regular saving when living in a passive home.
Moreover, most of the specialised materials needed to meet the Passive House Standard require minimal maintenance. They also have a longer functional lifespan than most standard materials, generally continuing to work as designed for 30+ years. As such, ongoing costs tend to be lower for a passive house than most other house types.
The final verdict
The question of whether building a passive house will be more expensive really depends on your point of comparison. If you are considering a standard design from a volume builder, a passive house will be notably more expensive. But if you are thinking about using a custom home builder, a passive house may not cost you much more.
Either way, it is clear that any additional upfront costs you incur should be offset by ongoing savings. This is particularly true if you are planning to live in the property for an extended period. As such, we believe a passive house can be a worthwhile financial investment, especially if sustainability is important to you.
If you would like to learn more about building a passive house, including how much it costs, contact Carmel Homes. We are passionate about sustainability and committed to finding ways to minimise the long-term impacts of our projects. As part of this, we can help you identify ways to boost both the liveability and efficiency of your new home plans.
