The pros and cons of building a Passive House
I think I warned you 2021 would be filled with lots of “we’re building a new passive house” blogs, right?
It’s been an exciting – and busy – past few months in the Tree Changer shousehold, with work on our new house now well underway.
Living onsite has many advantages. This includes taking and sharing photos every time something exciting happens – like seeing the floor framing get its termite cover (okay, maybe it was just me excited by this development – it was a slower month, okay!).
And as our house has started emerging from the ground on pillars, and not from a slab which is the usual method around here, we’ve had a lot more questions from both our neighbours and people watching the build from afar about what we’re doing and why it’s meant to be better than a conventional build.
So, for those that are interested, I thought I’d jump into the pros and cons of building a passive house. If you missed it, check out my original blog explaining what a passive house is in a bit more detail and why we’re building one here.
By way of a quick recap – a passive house combines thoughtful design and special materials and building techniques to create a house that uses very little energy but delivers a healthy indoor environment that is comfortable year-round in terms of temperature and humidity.
The Pros
Low energy consumption
To start with the obvious, one of the main benefits of building a passive house is a reduction in energy consumption and its associated costs.
Passive houses are designed to:
- capture and retain as much natural heat as possible and manage heat loss to minimise the need for heating (and cooling),
- use renewable sources of energy (i.e. solar panels with battery storage in our case) to support any power, and heating or cooling assistance, needed, and
- run with low energy appliances and lighting systems to further minimise energy use.
The figures we’ve seen suggest people’s energy consumption (and energy bills) have been reduced from anywhere between 75% and 90% when they live in a passive house.
Any savings are attractive, but this was definitely a selling point for us given we moved to the country to work (and earn) less.
An improved living environment
Another selling point of passive houses is they are designed to provide a comfortable living environment year-round, with high air quality.
To function, passive houses need to be completely airtight. To keep the humans inside it alive, they use a special heat recovery ventilation system that effectively swaps old air for fresh, filtered air.
When the stale air is removed, the system then transfers its heat (or coolness) to the fresh air brought into the home, controlling its temperature and the comfort of the humans living in the house.
Another benefit of passive houses being airtight (and appropriately ventilated) means mould should be a thing of the past too.
No unwanted housemates!
Okay, you probably won’t find this in the standard passive house literature, but a fully sealed, airtight house should also mean our current unwanted house guest (the brown snakes chasing the mouse brigade living in the shouse’s walls) should be a thing of the past.
This all sounds pretty awesome right? It must be time to hit you with the cons!
The Cons
Higher construction cost
While there’s not a lot of data (yet) to support this claim, it’s generally accepted that building a passive house is more expensive than building a house using traditional building methods.
There are a few reasons for this:
- there is A LOT of work and expertise involved in the initial design phase to get the orientation of the house and the materials it will use right, to ensure it takes maximum advantage of the site, sun and breezes for heating and cooling. There are programs that can help you do this yourself, but they’re not easy to navigate so you’re better off bringing in an expert IMHO.
- The materials needed can be more expensive. For example, we need to build with triple glazed windows – not something found inexpensively in Australia! We’re working with a fantastic builder, Eclipse Passive House. They have designed a modular system and building method to minimise costs and make building a passive house much more affordable, which is helping.
- The workpersonship and attention to detail needed can add to the cost. The need to build the house completely airtight adds complexity, given the builder needs to get the detail absolutely right up front. Unlike a traditional house, you can’t just cut a hole to run more plumbing or wiring missed in the original design as it compromises the airtightness.
While our build is costing more than average house builds in our area, we’re confident the energy cost savings and comfort achieved in the long run will ensure the upfront investment pays off.
Potential lower resale values
While more and more passive houses are being built in Australia, they are still a relatively new and unknown concept. The most recent figures we’ve seen suggest around 60,000 homes have achieved passive house certification, most of which are in Europe.
As a case in point, we recently searched passive houses for sale across Australia and came up blank.
Property valuers are often left scratching their heads to find comparable properties and sales. This is great if you’re selling and the market gets hot (which it’s expected to do in the next decade) but not so good if you’re relying on a bank to finance your build.
We’re building a house to live in for many years, so this con doesn’t really bother us, but it can be a significant consideration for many people looking at this approach to building, especially if you need bank help to fund the build.
Living complexity
We have been warned that living in a passive house will not be like living in a typical home!
We’ll need to learn when to open and close windows or close shades to help manage heating and cooling the house at certain points in the year. We’ll also need to learn all about the house’s ventilation system and how it needs to be maintained.
While this is relatively small in the scheme of things, we imagine it will take some getting used to and come with trials – and errors.
So that’s the pros and cons as we see them!
If you have any questions, leave them below & we’ll do our best to answer them!
And if you’re interested to learn more about Passive Houses, check out:
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