What will be covered in this article?

Building a sustainable home doesn’t have to be expensive. In fact, sustainable homes can (and should) be the cheaper alternative. Even if costs are slightly higher upfront, it’s likely you will save a lot in the long run.

This article describes five key steps to build a modern sustainable home on a budget:

Being realistic
Choosing the right block
Saving energy
Saving carbon in your materials
Managing costs

1. Being realistic

Building a sustainable home is all about finding the right balance between your needs and budget. How big does your home need to be? The smaller your home, the cheaper and more sustainable it will be. You don’t need to go tiny, but you do need to think about what you need from a home. Let’s look at the following project home for an average-sized family.

At 370sqm it includes a lot of rooms and features you may not use on a daily basis.

• 4 living spaces

• 4 bedrooms plus a study

• A mix of oversized and undersized rooms

• Large areas of unusable space dedicated to halls and circulation.

• A balcony with no purpose

Remember that average household size is 2.5 people and shrinking, and that construction, maintenance and energy costs are rising.

Consider the following questions:

How many bedrooms will you need?
How often do you have guests? Can a guest bedroom double up as a games room?
Is entertaining important for you? This will impact how large your kitchen, living and dining areas need to be.
Will you need a home office?
What ancillary spaces do you need such as storage rooms or garages?

Once you know how many rooms you’ll need you can decide between one or two storeys. While a double storey home might fit better on a small lot, they can be much more expensive when considering the stairs, extra bathrooms, and higher construction fees for above ground floors.

All this considered, it comes down to designing a beautiful, functional home with a good surface to volume ratio. You may need to make some compromises but you may also come out of this with a beautiful home that is compact, functional and sustainable

2 Choosing the right block

Now you’ve decided what you need from a home, you need to choose the right block.

Orientation

Which way is north? Ideally, living and outdoor spaces will face true north (+/- 15 degrees). This makes it easier to design a solar passive home that’s shaded from summer sun and warmed by winter sun.

Dimensions and Size

Can you fit the house you want? Block size may dictate room sizes and the number of storeys you will need. Be aware that planning codes specify required percentages of outdoor space. An R30 or R40 block requires 45% open space (so a 180m2 block can have a maximum 100m2 building footprint, including a garage).

Site Levels

There’s no point purchasing a small block to save money if expensive retaining walls and earthworks are required before you can start building. It may be better to spend more on a different block that’s ready to go.

Aspect

What can you see from the site? Can your lifestyle be enhanced with views to greenery, open space, or water? Your home should be designed to take advantage of views and there’s no point paying for great views to the south if your living area has to face north.

Access

How will you, your visitors, and your builders access the site if parking is limited? Is there an access leg from a nearby street? Is verge parking available? These can all Impact logistics and the costs of building.

Context

Small blocks are often overshadowed by taller neighbouring properties, and this can impact your living and outdoor spaces. If your home will be two storeys, state planning policy R-codes require privacy screening for all windows and balconies within a ‘cone of vision’ of a neighbouring property, which can affect the value of a balcony.

Regardless of size, these types of blocks are likely to be best:

Corner blocks with a long north boundary and no buildings blocking the sun or sky view from the living areas.
East-west oriented blocks with minimum 12m width from the street, allowing an east-west axis for solar passive design. On narrower blocks it can be difficult to provide rooms and outdoor spaces that get enough sun.
Blocks with a north facing rear boundary and street access to the south, allowing living areas and outdoor spaces to face north into a backyard.

If in doubt, consult with Leanhaus or your architect before purchasing a block. There may be hidden complexities that will impact the design, or great design opportunities that no one else can see!

3. Saving energy

Passive Solar and Passive House design methods sound similar, but are quite different ways to reduce operational energy (and your energy bills). Let’s look at them both in a bit more detail.

Passive Solar

Passive solar designs aim to maximise a building’s energy efficiency using orientation, building envelopes, thermal mass, insulation, ventilation and zoning (principles that should be applied to every project). But there’s no certification system to guarantee the effectiveness of passive solar design. Nevertheless, any good architect or building designer can achieve a passive solar design with no additional cost compared to a conventional design.

Passive House

Passive House is an internationally recognised best practice design and certification system. It is a fabric first approach that follows 5 main principles:

• Excellent Insulation

• No Thermal Bridges

• High performance windows and doors.

• Air-tight building envelope

• Mechanical Heat Recovery Ventilation

The resulting comfort standard provides:

• average air temperature of 21 degrees, and over 25 degrees for no more than 10% of the time

• surface temperatures should be higher than 17 degrees

• air leakage less than 0.6 air changes per hour when measured at 50 pascals (no draughts)

• fresh, filtered air all the time

• no draughts and no cold spots A Passive House is the gold standard of energyefficient homes.

The cost of a Passive House is around 5-10% more than the equivalent passive solar home.

Which one to choose?

A good passive solar house based on sound design principles doesn’t cost more if done right, but it won’t guarantee the efficiency that a Passive House does. At Leanhaus we offer three standards for energy-efficient homes, so you can choose the standard for a high-performing, energy-efficient house that best suits your budget and needs:

Ecohaus (high-performance using passive solar principles)
Leanhaus (same as Ecohaus but built airtight to Passive House standards) and
Passivhaus (certified Passive House).

4. Saving carbon in your materials

Sustainability means reducing both your home’s operational energy, and the energy that goes into building it. So what’s the total carbon footprint of your new home?

At Leanhaus we replace the most carbon heavy materials, including steel, brick, concrete and aluminium, with timber where possible. We also specialise in compact designs that reduce material load, saving both carbon and costs. These choices alone will reduce your new home’s carbon footprint significantly. We’re wary of some alternative and niche “eco-materials” available today, however they tend to come with higher cost and construction risk.

5. Managing cost

Architect-designed homes in WA typically start from $6000/sqm. At Leanhaus, we aim for $3,500-$5,000/m2, depending on the project size, complexity and level of finish. Smaller homes generally cost more per square meter but less overall. Here’s how we manage your costs.

Optimising your design

At Leanhaus we’ll help you find the right balance between design, quality, performance and cost by helping you determine your priorities. A more efficient design can offer the same functionality as a larger house but in a smaller footprint, saving a significant amount of money and operational energy.

We’ll work with a designated builder from day one

At Leanhaus, our relationship with builders is one of our greatest assets. We only work with a small group of select, Passive House certified builders, who are also carpenters. This means they will work on Leanhaus projects day in and day out, learning and improving all aspects of each project as they go. This results in more efficient construction and reduced risk for the builder, and will save you both time and money.

We’ll use the simplest feasible materials

Considering that more than 40% of the cost of your home is labour costs it’s not surprising that prices climb quickly when builders need to build unfamiliar architectural features or work with the newest, overhyped but unfamiliar “eco-materials”. This is why at Leanhaus we specialise in simple, effective and beautiful designs built using familiar but sustainable materials. This means our builders know exactly what they’re doing and won’t waste your time and money figuring things out.

Building a modern, sustainable home on a budget