Passive houses are energy-efficient homes designed to provide maximum comfort with minimal energy consumption. One of the most common questions we hear from those planning their passive house as passive house specialists is, “How much should I budget for a passive house?”, or “How much is a passive house?”. Well, the answer is not straightforward as there are various dependencies that will be particular to your site and home design to consider. To help you better estimate your passive house project costs, we break down passive house budgeting into 4 components:
- Design & Approvals
- Site-Specific Conditions
- Build Costs
- Interior Design
Our approach at Marvel Homes is to always provide transparency in pricing, breaking down costs throughout the design and build process. We find this particularly important for complex sites such as sloping sites, split-level sites and builds with basements. We have learnt from years of experience that breaking project costs into these 4 areas creates a framework to manage and maximise your entire project budget.
1. Design & Approvals
The first step in your passive house journey is the Design & Approval stage. It requires a preliminary scope of work to establish your project requirements. Using this scope, we formulate plans that match your site and suit your lifestyle. To develop these passive house plans, you’ll require a range of consultants, which may include:
- An architect/draftsperson
- Town Planner
- Hydraulic Engineer
- Building Surveyor
- Arborist – depending on your site
From our experience, these consultants are the bare minimum for every knockdown rebuild project. An Arborist may not be required, as this is only important if you have significant trees on your site that your plans need to account for.
While not every builder takes this approach, as passive house specialists we have found that prior to drafting any plans, engaging these consultants ensures that 90% of your site-specific conditions are covered, meaning your final drawings account for all site considerations.
Effective budget management for passive house builds is highly dependent on getting the right information, which begins in these early stages of design and approvals. Just remember, during this stage, your entire project scope is defined, and your house size is established.
2. Site-Specific Conditions
We pride ourselves on being an efficient passive house builder that approaches each project with a Kaizen mentality. Kaizen is a Japanese word meaning a mindset of constant improvement. Each and every one of our custom home builds follow stringent Passive House principles, adhering to Sydney codes and meeting Australian building and engineering standards. We adopt learning and improvement from each previous job and apply it to future jobs. Our custom approach ensures your project’s site conditions and specific challenges are addressed. This tailored approach is what makes each Marvel home unique.
However, each unique project has a set of specific site conditions. If we were to build the same house, in two different locations, the house build costs would be the same, but the site conditions might not be. Therefore, this passive house budget category captures costs associated with site conditions, which include but are not limited to:
- Street access
- Site slope
- Stormwater flow management
- Driveway slope and direction and required integration with the new design
- Neighbouring fence
- Soil removal
- Slab design complication
- Landscape design and management
These critical topics need to be addressed on a site-by-site basis, as every site will have its own specific solutions. This is why we separate these passive house costs, as most of these are variable costs that can’t be fixed until site investigations are carried out.
For example, during excavation, the neighbouring fencing may fall due to age or the original build not meeting standards. Or when excavating for the slab and stormwater pipes that manage water egress around your home, we might hit rock. Heavy rains may stop the dig halfway, causing dig delays that then require rework. These are just some examples that can occur when breaking ground on a building’s foundation, which is hard to account for until works or investigations commence.
Our approach is to always lay out the various requirements for your passive house site upfront, ensuring the right amount of contingency plans are put in place. Most construction cost variations arise from site-specific conditions. For this reason, we approach your site-specific conditions with as much detail as possible, as we don’t want clients to have any unwanted surprises down the track. This is a sensitive and critical area that most builders will shy away from in the early stages prior to contract signing, but at Marvel Homes, we work with you to get your plans as tight as possible from the get-go.
3. Build Cost
Once all approvals and site costs are complete, we price the passive build costs, which include everything above the slab. At Marvel Homes, we fix the build cost price for all our clients. This means that once the construction plans are finalised and signed off by you, there will be no additional costs added.
We can fix the build cost, as we are in control of the details. With each build component, a known quantity, it permits a very small margin of error. It is during this stage that we produce your construction plans. These passive house plans document all your home’s details, materials, interior elevations, facade specifications and more. Your passive house plans are what your construction team will follow on-site to ensure there are no variations, unwanted surprises or unclear areas of scope.
We detail building plans closely with all our clients, stage by stage, which is critical, as these drawings make for a smooth build process on site. Most of the time, when a set of plans are not well detailed, the passive house construction process can be delayed or halted altogether.
Be wary of plans that are not detailed and drawn by your builder, as this can create scope gaps that lead to variations. As specialists, we have learnt from experience that the building team needs 100% accurate documentation to ensure they are not figuring out details onsite. We understand that most clients may not be able to understand what is detailed enough or not, so to mitigate any design risks we ensure that adequate time is taken with your build team to go through every element, explain it all and answer any questions you might have. If you are considering a passive home build with a set budget, a design and build team is your best approach, as the risk is with us, the builder, and not you, the client.
4. Interior Design
Now that we have covered the sometimes stressful, but important areas of budgeting for a passive house build, we can work on the fun stuff. The interior design phase is where you own and make your home all about you, your style, and what you have always imagined for your lifestyle.
This area is sometimes called ‘selections‘ or ‘colours’ in the home building industry. For us, at Marvel Homes, we call it interior design, because we plan your home with a dedicated interior design consultant. You will work exclusively with your interior design consultant as they guide you through the process, taking you to all the major suppliers to select finishes, colours, materials and fixtures for your home.
Our design process is carefully considered to ensure the best possible results, following five main stages, including:
- Colour pallet session – an in-house session with your Marvel Home’s interior designer, this session brings to life your ideas prior to visiting showrooms.
- First showroom visit – Here you will select your main floor coverings, this sets the flow for the rest of your item selections.
- Second showroom visit – Kitchen stone and benchtop selection, here you work with your Marvel Home interior design to match your selection with your main floor selections.
- Third showroom visit – Tiles selection, an important step that complements all your previous selections.
- Fixtures, appliances and electrical goods – Finally, your interior designer will work with you to select the remaining items for your home.
Summary: Budgeting For A Passive House
If you are budgeting for a passive house, there are multiple components of your build that will need to be considered. As passive house-building specialists, we break budgeting into 4 areas including site-specific conditions, approvals and build costs. If sticking to a budget is a high priority for your family, we strongly recommend considering a design and build team like Marvel Homes that can advise, manage and mitigate budget risks for you from the start.
More about our passive house build process.