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Here’s why mass timber is the hottest new thing in sustainable building

The hottest new building material is timber

As the demand for new homes and buildings increases along with population growth, so too does our impact on the climate. According to a 2020 report conducted by WWF Australia, the built environment sector is responsible for one quarter of Australia’s emissions, with the steel and cement industries representing around 7% of global emissions. With the climate already in crisis, it’s clear that we need to find a more sustainable way to build, and fast.

There are many aspects that contribute to the carbon footprint of the construction industry, from production and distribution of materials, to the materials themselves, which is why a multifaceted approach is required if we are to see real and meaningful change. One aspect that is sparking plenty of interest and excitement in the industry currently is the potential for timber, in particular mass timber, to replace steel and concrete in the construction of buildings.

So is mass timber a viable and more sustainable way to build? In this article we take a closer look at some of the key considerations for architects, builders and homeowners who are designing, constructing and living in the buildings of the future.

What is mass timber?

Inside Corsica Panorama 18 Display Village Ourimbah 2020

Unlike standard stick timber that is cut into lengths and used for framing, mass timber is made up of multiple layers of timber that are stuck together to form larger panels or beams. Short for ‘massive timber’, mass timber is the term that’s used to describe a range of timber products that are made this way, including lumber glue laminate (LGL), laminated veneer lumber (LVL) and cross-laminated timber (CLT). Mass timber is generally made from softwood species such as
pine, spruce and fir, but can also be manufactured using some hardwood species like ash, birch and beech.

Why is mass timber a great choice for homes?

Iceland - dining living

All larger YZY Kit Homes are constructed entirely from laminated LGL timber that has been manufactured into precision cut parts for our kit homes. There are some key reasons why we work exclusively with it, which we’ve outlined below.

  • Structure and strength – LGL is the ideal fit for our tongue and groove interlocking design system, as it provides both structure and insulation. The structural strength of LGL timber is comparable to concrete and steel, remaining straight, stable and strong, even in harsh outdoor environments.
  • Negative carbon footprint – A big plus of mass timber over traditional materials is that unlike steel and concrete it does not have a high carbon footprint. In fact, when sourced from sustainable plantations and manufactured and built efficiently, it is more likely to have a neutral or negative carbon footprint. We have an article ‘Here’s Why Timber Homes are a Sustainable Choice’ with interesting figures on how much tonnes of carbon can be removed when building with timber.
  • Built-in energy efficiency – One of the things we love most about working with mass timber is that the solid timber walls of our homes act like thermal batteries, storing heat through the day before gradually releasing it at night. This creates a more stable temperature and avoids substantial temperature changes, which in turn reduces the need for artificial heating or cooling. You can read more about this in our article How Energy Efficient Are Solid Timber Homes?
  • Fast and easy to work with – Because mass timber is manufactured offsite, it can be crafted into parts of almost any shape and size, making it easier to transport, handle and build with.
    What’s more, many manufacturers of mass timber use computer numeric control (CNC) machines which allow for precise cuts every time. This means that when timber arrives on site, it is pre-cut and ready to construct without the need for time consuming on-site adjustments.
  • Performs well in fire – A common misconception is that timber homes are highly flammable. And while stick built frames and some timber materials might ignite and burn easily, mass timber is quite a different story. The air tightness and density of mass timber makes it perform differently, with the outer layer charring, but then extinguishing, protecting the inner layer from damage. This works in a similar way to how a large timber log behaves if you hold a match to it – it is extremely difficult to get it to burn.
  • Solid timber is strong in earthquakes – Another big plus of mass timber is its structural strength. It can withstand high winds and exposed sites, and its performance in earthquakes has been extensively tested and it has proved to be remarkably strong, as shown in the video below.
  • High resistance to floods – In general, if a conventionally built home is subjected to a flood, large sections of Gyprock will need to be replaced as a result of the water damage. However, a solid timber home will dry out once the water subsides and remain structurally stable, saving you the added cost and inconvenience of repairs.
  • Wood creates a healthy home – There is something calming and comforting about a home that is built from natural wood and you can feel the connection to nature. It is not only aesthetically pleasing and good for your spirit, it’s healthier for you and your family too. Interestingly, a report by Planet Ark found that timber interiors have numerous benefits to our health – from improved air quality by moderating humidity, to lower blood pressure and reduced stress levels.

The time for change is now

Sustainable Timber Homes

With the mounting pressure from the public on climate change action, now is the time for the construction industry to step up and reduce their carbon footprint. There are many touchpoints where positive change may occur, however, the clear benefits to the environment and our health and wellbeing suggests building with mass timber is a great place to start.

With the National Construction Code currently undertaking its three yearly review, there have been many submissions from both the public and those in the industry calling for the required standards of sustainability in new homes to be lifted. This is a fantastic opportunity to create sweeping positive change across Australia, and we are hopeful that the 2022 update will incorporate the suggestions that will guide the industry towards significantly lowering their collective footprint.

Crete Panorama 10 Display Village Ourimbah

Order Crete Panorama 10 before Christmas and save

Crete Panorama 10 Display Village Ourimbah

Do you need an extra room built in your backyard? Now could be a perfect time to order your eco-friendly pool house, home office or a backyard retreat before the prices increase after Christmas. We have our classic style cabins ‘Crete Panorama 10‘ (3.8 m x 2.8 m) in stock and they are:

  • Available for immediate delivery
  • Installed in just a few days
  • Features double glazed windows and doors
  • No council approval if installed as a pool cabana (NSW)
Continue reading Order Crete Panorama 10 before Christmas and save
Price change notice

Price change notice

You’ve likely heard the recent discussion around timber price and shipping issues which has been a growing concern for the construction industry and home builders around the world. A significant increase in demand for building products has put pressures on supply, which has led to timber prices climbing steeply.

This has been largely due to the pandemic, which has caused havoc and disrupted life and the economy worldwide. As a result, the following factors are impacting YZY Kit Homes price and supply:

Continue reading Price change notice
Brett Cowan owner of home office, Brisbane, QLD

Home office installed within a week in Brisbane, QLD

When the isolation phase of COVID-19 required individuals to work from home, Brett Cowan needed to temporarily manage his city-based business from his garage.

“Obviously this option wasn’t the most attractive, but with a 4 bedroom home and our 3 children rightfully filling every space, it was actually the only one I had,” Brett explains.

Continue reading Home office installed within a week in Brisbane, QLD
Finished Susie's Madeira

Building the Madeira Granny Flat as an Owner-Builder

Building a granny flat or backyard cabin as an owner-builder is an exciting and rewarding experience—but if it’s your first time, it can be a little daunting too!

So to give you some insight into where to start and what needs to be done when, check out this short video made by our client Susie, and the accompanying article, where she shares her experience of managing her Madeira granny flat backyard project.

Continue reading Building the Madeira Granny Flat as an Owner-Builder
NatHERS

How Energy Efficient are Solid Timber Homes?

With the increased focus on sustainable living in recent times, the energy efficiency of new homes has become a hot topic. A home that uses less energy has less impact on the environment and on our back pocket, which is something we’d all like to include in our new home builds.

However, the trouble is that when it comes to building an energy efficient home, the ratings and requirements used as a standard can be confusing and may not tell the full story. This is particularly true when it comes to solid timber homes—currently there is no formal way to assess their actual energy efficiency in Australia, which often means they are undervalued.

So, if you’re considering building a solid timber home but are looking for clarity around just how energy efficient they are, read on as we share some key tips that can help guide your decision.

How is energy efficiency in homes rated in Australia?

The standard national energy efficiency tools used across Australia are The Nationwide House Energy Rating Scheme (NatHERS) alongside the mandatory energy efficiency requirements set out in the National Construction Code (NCC). The trouble with the NatHERS system is that R-values are the only measure used to determine effective thermal performance—but in solid timber homes, the actual thermal performance is often higher than the steady-state R-value shows due to the ‘mass effect’.

In New Zealand, the importance of mass effect is recognised by a Building Code Clause that allows for alternative minimum R-values for solid timber construction where the thermal mass of the building must be taken into account.

What’s the difference between R-value and mass effect?

When there is a difference in temperature between inside and out, heat will conduct from the warmer side into the material, then slowly move through to the colder side. The R-value measures this resistance to heat flow in a steady state, which applies when the temperatures are constant.

However, in reality, there is often a fluctuation between temperatures both inside and out, depending on the time of day, season and climate. This will alter or even reverse the direction of heat flow, sometimes multiple times in the course of a day. Under these conditions, the shifting heat flow results in less heat transfer, giving walls made from high-heat capacity materials such as solid wood, a thermal performance which is more effective than the steady-state R-value shows. This dynamic process is referred to as the mass effect.

Another situation where mass effect comes into play is where the outside temperature changes but does not cross the indoor temperature. In this case the direction of the heat flow stays the same, and the time delay or thermal lag creates efficiency by delaying the peak heating or cooling load. While this will not affect the amount of heat flowing through the wall, the lag can save energy and reduce running costs.

A study on the energy performance of log homes backs this up, finding that although they often have lower steady-state R-values, log walls have been shown to provide equal or superior annual heating and cooling performance when compared to lightweight wood frame walls. For example, a log wall with a R-9 value performed similarly to an insulated lightweight wood frame wall in a temperate climate with values of R-13 to R-15, for both heating and cooling loads.

Which factors impact energy efficiency ratings?

Custom designed - living room
Custom designed – living room

NatHERS energy ratings take into account a wide range of factors when determining the rating, including the location, orientation, subfloor, roofing, lighting, ceiling fans, flooring and even the colour of the external walls. There is no generic ‘one size fits all approach’ and with 69 different climate zones identified by NatHERS across Australia, the results can be widely variable.

How energy efficient are YZY Kit Homes?

YZY Kit Homes are constructed with timber mass walls, which act like ‘thermal batteries’, storing heat during the day and gradually releasing it at night. This makes our cabins and granny flats an eco-friendly and energy efficient choice that will benefit you and the environment for many years to come.

LGL laminated timber, glulam
YZY Kit Homes are built with solid wood LGL timber

To achieve your desired energy efficiency, there are two options:

1) Build your cabin or granny flat with 60mm, 80mm, 95mm, 120mm or 140mm thickness LGL walls that will not require extra insulation, even in the hottest or coolest regions of Australia.
2) Have a minimum thickness of the walls required structurally, with external cladding or internal lining and extra insulation added in between. Cladding options are available that are low (or no) maintenance and some can also be fire resistant.

What are the NatHERS ratings on YZY Kit Homes?

Iceland Display Village Ourimbah 2020
Iceland 2-bedroom granny flat, Ourimbah Display Village

As discussed, there are many factors that impact how the NatHERS rating is calculated, which means the rating of your home will always be project-specific. In addition, the actual energy efficiency and comfort felt living in our cabins and granny flats will be better than the ratings reflect, owing to the mass effect of our solid timber walls.

As a guide, below you’ll find some indicative ratings on our designs when built in certain conditions and climates.

NSW climate zone 15 (Central Coast NSW):
Iceland design built with 60mm walls on concrete slab = 7 stars, with 80mm walls = 7.9 stars.
(A pass for this climate zone is approximately 5.2 stars.)

TAS climate zone 26 (Hobart)
Greenland design built with 80mm walls = 6.4 stars
(A pass for this climate zone is 6 stars.)

ACT climate zone 24
Iceland design built with 80mm walls = 6.1 stars, 95mm walls = 6.7 stars.
Greenland design built with 60mm walls with insulation added to 3 walls = 7 stars.
(A pass for this climate zone is 6 stars.)

Note: A passive house must not exceed a total combined heating plus cooling demand of up to 108 MJ/m2/year (108 MJ is equivalent to 7.3 star NatHERS design in Canberra.)

There’s more to energy efficiency than a rating

While the NatHERS ratings provide some useful insights into energy efficiency, it’s important to be aware that there are other factors that impact the actual efficiency of buildings, in particular, those built with timber mass walls.

In the future we hope for a similar building clause found in New Zealand to be introduced into Australia which recognises the difference in rating thermal efficiency in timber mass buildings. Until then, it is up to the consumer to look beyond the ratings, and for the builders to continue to educate, to be sure the energy efficient homes being built are the best they can be.

Upcoming NCC update

The NCC is updated every three years based on regulatory practices, industry research and public feedback. The next update is planned in 2022 and the Australian Building Codes Board (ABCB) has opened consultation on stage 2 of National Construction Code (NCC) 2022 public comment. Responses are invited until 17 October 2021 and can be accessed here.

This stage of consultation seeks comment on proposed NCC amendments on energy efficiency and condensation. A consultation link was sent to all registered NCC Online users on 30 August 2021. We will submit our comments to the ABCB, to advocate for the energy efficiency of timber mass homes to be taken into account. Our recommendations will include the introduction of a clause that accounts for the importance of mass effect and allows for an alternative to minimum R-values for solid timber construction, similar to New Zealand’s current Building Code Clause to that effect.