Keeping cool without air conditioning - a guide for new homes

Keeping cool without air conditioning - a guide for new homes

As the climate heats up, more and more people will be turning on the AC to keep cool. By 2050, up to two thirds of households globally will have an air conditioner, and unless the energy to power these is from sustainable sources, more and more greenhouse gas emissions will be generated which will in turn, contribute to more global warming.

But there is a way to design buildings to keep a comfortable interior environment with resorting to AC. Here are some of the strategies we deploy at Leanhaus.

Lets Talk about about SIPS

What are SIPS?

A structural insulated panel (SIP) is a form of sandwich panel used in the construction industry. A SIP is a sandwich structured composite, consisting of an insulating layer of rigid core sandwiched between two layers of structural board, used as a building material .

Sips panel.jpg

Some of the arguments for building with SIPS include:

  • Faster construction

  • Less waste

  • High R-value.

  • Integrated Structure

Should you use SIPS on your new home?

Being open to new technology and innovation, I looked into it using SIPS my own house. I even designed a version of the house using SIPS and then got it priced for construction to compare with a timber framed home of equal performance. Here is what the process taught me about SIPS.

  1. Time Saved - is it worth it?

    The time saving may not be worth the additional cost of the SIPS products over timber frames. In construction terms, erecting the building structure only accounts for a portion of the overall build program. A site based carpentry team can erect a two storey timber home structure and make it weather tight in around 4 weeks. Prefabricated Frames can be erected in under a week. A SIPS build house claims to achieve this in 1 to 2 weeks. At best, a saving of 1 to 3 weeks over a 6 month build isn’t significant enough to justify the extra cost and complexity of SIPS, especially if you have to wait for a production slot for your panels to be manufactured, checked, delivered to site and erected.

  2. SIP Suppliers and Pricing

    There is limited number of SIPS panel suppliers around which means that there is a lack of competition in pricing. WA for example has two active SIPS panel providers, both of which have their own product composition, module dimensions and installation methods. These suppliers are relatively small without the large economies of scale to make SIPS pricing cost effective overall.

  3. SIPS Installation

    There is a limited number of tradesman with experience in SIPS so it is hard to get a price for construction that isn't loaded with risk. It is not just about the SIPS install itself. Builders, Electricians, Plumbers, Engineers, Air Con Installers are just a few of the contributors to your home that will have to adjust to working with SIPS, and in our building industry unknown factors ring big alarm bells. Every trade that deals with this unknown will want to add time and cost to your project cover the risk.

  4. SIPS material efficiency

    SIPS works particularly well when the home is designed specifically to the standard panel sizes in order to minimise wastage. This takes a significant amount of additional time and cost in design phase.

  5. SIPS - all or nothing

    If you do design specifically for SIPS, but later find the cost of building with SIPS is too costly then you are stuck with drawings that should be modified due to different wall thicknesses and detailing needs.

    Also, Being a composite structure SIPS structures are difficult to modify later (you cannot simply remove walls or peel back cladding to add extra wiring for example).

  6. SIPS Durability

    SIPS are untested over long periods of time. Some SIP builders use silicon sealant to connect the panels. Over time this will degrade and allow water ingress. A NSW based company using SIPS recently went bankrupt due to a high number of their homes forming mould after installation. Mould in any home is massive issue, but in a SIPS home it is unfix-able. Water may even get inside the skin of SIPS as the home is being erected, but the issues wont arise until much later after the builder has left the scene and the warranty period has expired.

  7. SIPS and building health

    When the water does inevitably get in, the moisture has no way to leave the composite structure. This results in mould and material degradation. Mould in buildings is a serious health issue and can significantly impact the well being of occupants. The timber framed walls in a Leanhaus are designed to allow the structure to breathe so they can dry out even in the unlikely event moisture does get in down the track.

  8. SIPS and sustainability

    The individual materials that make up SIPS (foam, OSB, FC Sheet) cant be recycled due to the foam being bonded to the outside skins. This make recycling the panels cost prohibitive.

A SIPS building should be designed to use the manufactured module size in order to minimise waste.

A SIPS building should be designed to use the manufactured module size in order to minimise waste.

For all the above reasons Leanhaus has rejected SIP based construction in favour of timber frames. We can achieve similar levels of insulation with air tightness almost as fast and more cost effectively than SIPS. We also use prefabricated timber wall panels, which can save considerable time and cost on a typical project.

Leanhaus is established to provide the right balance of cost, quality and flexibility based on many years of experience, research and knowledge around design, sustainability and construction.

Feel free to get in touch if you have any questions.

The Problem with McMansions....Why big isn't necessarily best!


Many clients are torn between building a smaller, more sustainable home or a larger home with all the bells and whistles.

A general misconception people make about re-sale value is that a bigger house is better. This is the argument that real estate agent’s push so they can tick every possible box for potential buyers. But what is a large home really costing you?

Firstly there will be the inevitable trade off between quality and quantity. Many builders can provide you with a large home for a very competitive rate per square metre. But if the home is not designed to function or perform well then you may not be creating the resale value you are looking to achieve.

Clients often bring me their plans from builders that are inherently flawed and inefficiently designed. Rooms with a single purpose, oversized or poorly located spaces and acres of unusable circulation all contribute to an area blowout. Sure, the cost per square metre rate looks attractive, but it is not good value if the house is 25% larger than it should be and quality, functionality and building performance are lacking.

An investment in good design will always have better resale value, maintaining buyer appeal for years and standing out from the crowd of average homes in the market.


McMansion Hell - A look at a 370sqm home offered by a premium Perth builder

So why are large homes losing their appeal? Isn’t it the great Aussie dream to have a 2 car garage, 4 beds, 3 baths, a study, a theatre, scullery, parent’s retreat, teen’s retreat and an outdoor kitchen?

Well, household sizes are getting smaller and the population is getting older and want more manageable homes.

Its getting more and more expensive to operate a home with maintenance, power costs and cleaning.

Society is moving away material pursuits in favour of collecting experiences. A smaller, more cost effective home allows more of your time and resources to go on the things you enjoy doing such as hobbies and travel. The tiny house movement is growing globally based on this very philosophy.

People are becoming more educated about energy efficiency, building health and comfort. A smaller home may allow you to invest more in the quality of the building with higher levels of insulation, double glazing, high quality low maintenance materials, and features like ventilation systems that enhance your well being. Just as consumers are demanding safer, more fuel efficient and higher performance cars, they will expect the same of their homes.

And just like a new car, your new home starts to depreciate as soon as you build it.

In most cases it is only the land that appreciates in value. If you build a larger home, nobody wants to pay for extra space they don't need, but they will take it if it's included in the sale price!

An oversized house is like choosing a motor home as your daily driver. Yes it comes in handy for a few weeks a year (when the family visits), but it is unnecessary and expensive the rest of the time. A large but lesser quality home is the definition of overcapitalising. After all, who looks at a ten year old McMansion with envy!

On the market, Perth. This is what a large builder’s home looks like ten years later. Bloated, dated, ugly.

On the market, Perth. This is what a large builder’s home looks like ten years later. Bloated, dated, ugly.

When confronted by a quality vs quantity equation for your new house, focus on what you actually need and make the layout flexible for changing circumstances. Work on achieving the the best quality design and build you can afford. A small investment in an Architect will pay dividends in assisting to to weigh up all your competing desires and requirements and provide a workable solution for your new home. This home will bring pleasure and comfort everyday and will be more desirable when it is time to sell. 

A mid century Architect designed home in Floreat. Modest and 55 years old but still relevant, functional and desirable.

A mid century Architect designed home in Floreat. Modest and 55 years old but still relevant, functional and desirable.

What’s so wrong with new homes today?

Looks modern - but homes like this are really no different than brick homes from 100 years ago.

Looks modern - but homes like this are really no different than brick homes from 100 years ago.

You wouldn’t think of going to the car yard and buying a brand new version of gas guzzling car from the 1950’s… Well unfortunately most new homes today are the equivalent of a 1950’s car; inefficient, archaic design, materials and construction technology, and generally unhealthy to live in.

Home construction has not improved much in the last century. Double brick construction was originally introduced to WA because raw clay material was plentiful, and the labour force from England was familiar with brick laying. It was easy, fast and cheap. Bricks were solid and provided occupants with something of a thermal buffer from moderately hot and cold climates.

Fast forward to modern day and bricks are now hollowed out to save clay. Unfortunately this takes away the key benefit of using bricks - thermal mass. In real terms this means that a typical brick home today is worse than a home built 100 years ago. If it wasn’t for reverse cycle air conditioning, most new homes wouldn’t meet a minimum standard for comfort.

Fast Wall Brick

Fast Wall Brick

Even new homes built to the building code perform quite poorly in comparison to what is available in other developed nations.  The Australian NatHERS energy rating system currently in use is deeply flawed, easily ‘gamed’ by builders and assessors and doesn’t ensure your building will perform as expected, or be healthy and comfortable to live in. source

The pursuit of a high star rating will not necessarily result in a high performance home, as is evidenced in a number of projects.

The NatHERS calculation is open to significant error. The calculation is undertaken at design-stage and is rarely verified following construction. It is common for projects designed as 6 Star or above to be realised as 1-2 Star in reality; the result is thermally under-performing buildings, high energy costs, increased carbon emissions, and, ultimately, unhappy consumers.

In other words, as a new home buyer it is generally impossible to know if you are getting what you pay for.

At its core, the designer, builder and energy assessor are using flawed building analysis tools and archaic construction techniques in the hope that they design and build a home that is comfortable. You cant exactly get a refund on a new home if it fails to perform, so it is little wonder air conditioning and underfloor heating gets installed…just in case. But why spend the money on add-ons when you could just design and build the house right in the first place?

The way forward

To deliver a sustainable and comfortable home that does what is expected, a more sophisticated, scientific based approach to design, analysis and construction is required.

After years of practise and research, we found that the Passive House standard from Germany provides a proven scientific method for achieving healthy and comfortable homes for the WA climate. 

Previously only available to knowledgable clients with large budgets, we have developed the ideal construction method for WA's warm temperate climate. Timber Framing is superior to brick in many ways. Fast, robust, cost effective and materially efficient, Leanhaus sets the standard for health, comfort and efficiency in WA.

Ever since the creation of the world's first Passive House (or Passive Haus) in Darmstadt-Kranichstein, Germany 30 years ago, Passive House has been the leading standard for energy efficient, healthy, comfortable, economic and environmentally friendly buildings worldwide. 

It has become an increasingly recognised benchmark due to its ability to verify the quality of construction, ensure indoor comfort, and reduce operational energy consumption for heating and cooling by around 90% in comparison with an equivalent legally prescribed building standard.

Passive House relies on careful design and the integration of special construction systems to deliver a superior standard of building with higher quality construction, reduced energy costs, better occupant comfort and improved indoor air quality.

Leanhaus’ building methods have been specifically designed to incorporate Passive House requirements and includes a highly insulated building envelope with a ventilated facade. It also includes specialist air tightness barriers, which control air loss and vapour infiltration, as well as minimised thermal bridging through timber framed construction.

Leanhaus offers an integrated approach to design and construction, with consideration to the Passive House standard from the earliest stage. Careful consideration of siting and orientation, together with local climatic conditions, are used to identify optimum energy efficient solutions.

For a more scientific description of Passive House, continue reading here.

Lean design and construction - the Leanhaus way

Lean design and construction - the Leanhaus way

Lean design and construction is, according to one definition, "a production management-based project delivery system emphasising the reliable and speedy delivery of value. It challenges the generally-accepted belief that there is always a trade-off between time, cost, quality and safety." At leanhaus, we seek to apply these ideas to the design and construction of homes and small buildings to make them more affordable, durable and comfortable. Here’s how we do it.

air quality monitoring at home

air quality monitoring at home

We spend 90% of our time indoors, but indoor environments are typically 5x more polluted than outdoors. Dust, mould, expired air, CO2 and contaminants from cooking all create an indoor environment that contributes to allergies, asthma and sleep disturbance.  Rather than wait until suffering from health symptoms, it makes sense to monitor the air quality of your indoor environment.

Open those windows!

A common misconception about Passve Houses is that you cant ventilate them naturally by opening windows. Nothing is further from the truth. Let us explain…

Passive House is a comfort standard that seeks to maintain optimum internal comfort levels with minimum energy use. So if the external temperatures are amenable, open your windows! Let that breeze through your house and enjoy the indoor / outdoor lifestyle that Perth is famous for.