So you’ve decided to renovate your home…

With the assistance of homeowner stimulus packages and a current uncertainty around the climate for home buyers in the Melbourne area on top of restrictions imposed by COVID-19 and an increased amount of time at home to notice how you might like to change things, it is quite understandable that you would want to renovate your home.

What effect does renovating have on your home? Does it make any sense to inject money into this asset? Is it more than just the look of the home which is going to add value in the future? What is the deeper purpose of renovating an existing building and more particularly your home?

Beyond an update in décor, aesthetic, vogue and fancy, a home is primarily a shelter and a place to retreat from weather and public life. The secondary reason a dwelling exists is for comfort and wellbeing. The tertiary reason the dwelling exists is its beauty and aesthetic. It is inline with these levels of purpose (primary, secondary and tertiary) where the most value is provided to the homeowner.

A dwelling which exists is already a shelter and arguably satisfies its primary purpose. Tackling the secondary purpose of comfort and well-being is going to provide you with an arguably better value than just targeting the tertiary purpose surrounding aesthetic. Targeting both secondary and tertiary purposes may prove more delightful overall, depending what your intent and focus is.

What does it mean to make a dwelling comfortable? What is well-being?

There is a huge push for better performing buildings, better indoor environments and better professional practices in maintaining a high standard in these areas. The smaller you build, the more you can spend per square metre and the larger you build, the greater the detriment you are likely to cause to the environment. As designers of dwellings, we are able to fine-tune your particular budget and encourage you to take a direction where space is comfortable and healthy.

Numerous energy standards across the globe consider thermal comfort to be in the vicinity of 20 to 25 degrees. Some more on the lower scale, some on the higher scale and some over the whole range. It takes energy to maintain a comfort balance, particularly in Melbourne where we can record both sub zero and above forty-degree temperatures throughout the year.

Heating up to 20 degrees and cooling down to 25 is what consumes the most energy. In Winter it is the insulation of your Floor, Walls and Roof and the thermal performance of your windows which make the biggest impact in retaining heat within the building. In Summer it is adequate shading and a well-ventilated and insulated roof which contribute to maintaining a cooler climate within the building. Heat and light passing through glazed elements also greatly contribute to the performance of the internal spaces.

Measuring heat gains and subtracting the heat losses provides you with a very good understanding about which parts of your home have the best performance and which perform poorly. Beyond good insulation of the building envelope, you are now able to calculate the amount of heat and coolth you require to keep your home comfortable. It is with these two calculations you can work out the upfront cost of insulating your home and the recurring cost of heating and cooling your home.

Studies have shown that we spend 90% of our time indoors[1] and 60% of our energy usage is for space heating and cooling and hot water[2].

In Melbourne daily supply charges could be estimated at around $1 per day[3] and a cost per kWh could be estimated at 25 cents[4]. The average usage per day for a family home in Melbourne is 29.4kWh[5]. Therefore, the average cost per year is $3,053 for that family home based on the numbers above.

If we could halve the space heating and cooling energy consumption, we would be looking at a saving of $808 per year. If we can reduce energy consumption of heating and cooling and hot water by 75% as estimated in Australia by the Australian Passive House Association[6] it would be a saving of $1,211 per year.

If we are able to eliminate the use of a heater and air-conditioner and install a heat pump hot water system (and hopefully one with CO2 as the refrigerant) and in doing so reduce the energy consumption of space heating and cooling and the heating of water by 90% as is shown in Europe[7] we end up with a saving of $1,453 for a family home in Victoria.

So what is the cost of insulating your home?

Enviroshop has a price range available[8] and it is also important to add additional things like membranes to protect the insulation and your home from the weather. Using both the costs from Enviroshop, additional items and labour which is necessary, here is an opinion of the probable cost per element of the dwelling for a weatherboard home.

A cost per square metre could be; Floor at $90, Walls at $100 and Roof at $120 including cleaning and demolition, insulation, installation, membranes and reapplication of cladding and linings. External Wall area is generally double floor area and an inclined roof is around an average of floor area plus 30%. Using these numbers, we have an estimate of $446 per m² of floor area. This is an estimate to accommodate thermal performance with the intent of reducing energy usage by 75%.

Let’s go back to having a look at the $25,000 grant. Using the value of $446 per m² we are able to insulate a floor area of around 55m² with that grant. For smaller inner-suburban homes this goes a fair way to covering the cost of upgrading insulation to half the house. In the average sized home of 230m² it covers around 24% of the cost.

Not covered in these costs are the upgrade of Windows. Windows are often the poorest performing part of the thermal envelope in cooler climates. Windows have a huge cost range and it really depends on the manufacturer’s overheads, processes and material sources. As a guide, it is advisable to look at a cost per m² floor area of between $100 and $450 to replace all windows in a home with high performing airtight windows supplied to projects in Australia. Installation costs are likely to add around $30 to $40 to the window supply rate above.

Is there any value in making the home look good as well?

Yes. Absolutely. The notion of good is subject to the taste of the occupant and the notion of value is the amount of investment one makes to achieve the good outcome.

The comfort of the home, though largely driven by the performance of the thermal envelope is also increased with access to light, a sense of enjoyment within the spaces and a sense of ergonomic efficiency about the spaces inside. It is, as mentioned earlier, the tertiary purpose of a dwelling and is akin to the trait of self-appreciation and self-indulgence prevalent in human nature.

Within beauty and aesthetic, we find light, space and art. Light is the connection with nature from within the dwelling, space is the connection of the human scale and senses within the dwelling and art is the connection with delight and appreciation for creativity.

Each aspect of beauty and aesthetic can add value to the home by embellishing the primary and secondary purposes of a dwelling. Light provides a connection to something bigger and boundless which reinforces the comfort provided by the home. Space provides well-being to the human psyche and reinforces us not to fear, though rather be comforted and acquainted with our dwelling. Art adds delight to both the notion of shelter and the comfort of our internal spaces.

Any stimulus has the power to provide more benefit than initially anticipated when forward planning is considered and the effects of expenditure are assessed. Prioritising the building envelope increases the ability to impact running costs of the home way into the future. Therein also lies the possibility that the investment will pay itself back over time.

[1] https://www.environment.gov.au/protection/air-quality/indoor-air#:~:text=It%20is%20generally%20recognised%20that,%2C%20offices%2C%20or%20inside%20cars.

[2] https://www.yourhome.gov.au/energy

[3] https://wattever.com.au/electricity-daily-supply-charges-comparison/

[4] https://www.canstarblue.com.au/electricity/electricity-costs-kwh/

[5] https://ahd.csiro.au/other-data/typical-house-energy-use/

[6] https://blog.passivehouse-international.org/benefits-passive-house-buildings/

[7] https://www.passipedia.org/basics/what_is_a_passive_house (Measurement Results)

[8] https://enviroshop.com.au/pages/home-insulation

Image credit: Geoff Driscoll Architects on a Dual-Occupancy we worked on together.