Energy Efficiency on the She Renovates Podcast

“Unlock the secrets to creating comfortable, sustainable homes without breaking the bank!
Join us as we delve into the world of Passive House design with Audrey Whisker, director of Whisker Architecture.
Discover practical tips to save on time, money, and energy bills while transforming your space into a cozy haven.
From DIY insulation hacks to maximizing natural light, Audrey shares invaluable insights to elevate your home's efficiency.
Don't miss out on this episode of She Renovates, where we bridge the gap between profitability and purposeful living.
Tune in now!” - She Renovates Podcast

Passive House or PassivHaus - It's a great option for your home.

She Renovates Episode Show Notes

• Please start by sharing a bit about yourself
  I’ve wanted to be an architect since I was 11 when I was redesigning floor plans from home lottery brochures, and have a particular interest in how spaces influence how we act. My husband is also in the industry. He’s a site foreman with a background in carpentry and we have two large german shorthaired pointer dogs, Trixie and Hans.
  I launched Whisker Architecture in September 2020, and we’ve grown to a team of four. Since launching we’ve been fortunate to work with homeowners, businesses, schools, and government departments.
  At Whisker Architecture we  focus on designing beautiful spaces for people to Live [in] their Values. We believe aligning our spaces with our values builds capacity for empathy, kindness, and generosity - and who wouldn’t want a world with more of that?

• You shared with me that a number of elderly people die from inadequately insulated homes each year, can you elaborate on that please?
  Every winter in Australia there is a spike in deaths across the country - a 14.7% increase over other seasons. Various studies have linked this to increased stress on the cardiovascular system and increased risk of respiratory diseases when we get cold. “the rate of mortality due to thermally inefficient housing and cold weather is 6.5 per cent, almost double that of Sweden (3.9 per cent)” - CSIRO The people most at risk of mortality are society’s most fragile, including our elderly.
  For most people 20-24°C is considered a comfortable temperature. If the outside temperature in Melbourne’s (relatively temperate) winter, for example, is 6-13°C then your home needs to be well insulated and/or heated to not fall below that comfortable 20-24°C temperature band and into a state of stress.
  The cost of heating is a burden not all Australians can afford, particularly with the rising cost of living, so we most often hear of elderly and financially stressed people as the fatalities.
  The Building Code of Australia introduced basic energy efficiency measures in 2003. Before these standards were introduced the average performance of housing was found to be around 1.5 stars. Since then the requirements have been steadily improving the building quality of homes in Australia. On 1st May 2024 a minimum of 7-star Nathers rating will be required for all new builds.

  • Various sources here:
    1. https://ahd.csiro.au/australias-still-building-4-in-every-5-new-houses-to-no-more-than-the-minimum-energy-standard/ 
    2. https://www.sciencedirect.com/science/article/pii/S2214629623001846
    3. https://www.uow.edu.au/media/2021/die-of-cold-or-die-of-stress-.php
    4. https://www.abc.net.au/news/2017-08-09/fact-check-australia-sweden-winter-fatalities-heating/8780588
    5. https://theconversation.com/sustainable-housings-expensive-right-not-when-you-look-at-the-whole-equation-60056
    6. https://www.csiro.au/en/news/all/articles/2021/july/passivhaus-free-running-design-principles

• What is a passive house?
  First let me clarify that a Certified Passive House is not the same as a house that uses Solar Passive Design Principles.
  Solar Passive Design Principles include facing the house the optimum direction for sunlight, shading in summer while letting winter light in, smart use of thermal mass and cross ventilation. All very important for every house design.
  A Certified PassivHaus is a building that meets the rigorous standards set by the Passive House Institute (PHI) and is independently certified to meet those standards.
  To be certified as a Passive House, a building must meet specific criteria, including extremely low energy consumption for heating and cooling, high levels of insulation, airtight construction, high-performance windows, and efficient ventilation systems. These criteria aim to create buildings that require very little energy for heating and cooling, resulting in significantly reduced energy bills and environmental impact compared to conventional buildings.
  Unlike our standard Nathers Star System, Certified Passive Houses undergo thorough on-site testing (including a blower door test) and verification processes to ensure the built outcome meets the stringent standards set out during the design stage.
  The Passive House Institute also provides a renovation certification category which has slightly reduced requirements as it’s difficult to get older buildings as well insulated or quite as airtight.
  We don’t necessarily recommend Passivhaus certification for all of our clients - sometimes it will be out of reach financially or practically. We do recommend everybody learning about Passivhaus as a system because it breaks down the building science into:

  • Minimal energy consumption

  • Unbeatable thermal comfort

  • Superior air quality

  • Understanding the ROI calculations

• Speaking from the point of view of renovators: If you were going to make a list of improvements you would make to a house to reach passive status, what would they be?
  Achieving Certified Passive House - even the reduced renovation requirements is very difficult. If we broaden the question, the first steps to renovating for a High Performance Home are:

  • 1. Hire a professional team to suit the extent of energy efficiency you want to achieve - including an energy assessor (Nathers) or Passive House Certifier. Remember “what gets measured matters”.

  • 2. Put that wooly blanket on - increase insulation in the floor, walls, and ceiling.

  • 3. Plug those holes - wrapping the building and plugging as many - even small holes as possible will draft-proof the building.

  • 4. Improve those holes in the building envelope we want to keep - e.g. windows -  installing double glazing with either thermally broken aluminum frames or uPVC frames,

  • 5. Remove all inefficient appliances including gas or electric heating and replacing with heat pump technology.

  • 6. Test to ensure the Air Changes Per House (ACH) are as low as possible. If we achieve 5 ACH or less we must install a heat recovery ventilation systems so you are not losing energy for the sake of fresh air.

• If a homeowner did not have the financial capacity to do everything, how would you prioritise?
  A great way to renovate for energy efficiency on a budget is to focus on these easy DIY items:

  • 1. Increase the insulation in the walls, under the floors, and in the ceiling. If you’re planning on doing this yourself please familiarise yourself with the safety equipment and not install alone or in hot weather.

  • 2. Draft-proof the home with flexible sealant - paying particular attention to joints around windows, architraves, skirting, and cavity sliding doors. Refinishing old timber floors can help with any drafts through the floorboards.

  • 3. Don’t forget door and window seals. These are often available at local hardware stores and easy to DIY install.

  • 4. Install draftstoppers or backdraft stoppers to your exhausts - including kitchen, bathroom, and fireplaces. Remove your old inefficient gas appliances for heat pump units and split systems and plug those old wall vents too.

  • 5. Heavy curtains with pelmets or close-fitting blinds that restrict air-movement at windows creates an air pocket that slows heat transfer at windows. If that’s outside of the budget bubble wrap can work wonders and a little translucent film on the outside makes it less obvious from the street.

• Can you speak to the ROI of these improvements?
  These minor improvements on a friend and fellow architect's house, Sarah Lebner, improved the star rating of their home from 2.9 stars to 5.7 stars for less than $20,000. This represented roughly a 60% reduction in heating and cooling energy consumption.
  A Certified Passive House would expect to reduce the total energy consumption of the home by up to 90%.
  The ROI payback time will depend on how much you’re investing and how long you plan on living in that home.

  A study by the Centre for Urban Research found that for a Department of Health and Human Services found that for their social housing 8-star homes had the best return on investment for them. (Link to study: https://cur.org.au/cms/wp-content/uploads/2016/08/horsham-final-11.pdf )

Renovation Case Study

Existing Home: 2.2 stars

Option 1 - Star rating: 4.3 stars

- R6.0 to the ceiling
- No insulation to walls / floor
- Timber windows to North and South, uPVC to remainder

Option 2 - Star rating: 4.6 stars

- R6.0 to the ceiling
- R2.5 to the floor
- No insulation to walls
- Timber windows to North and South, uPVC to remainder

Option 3 - Star rating: 6.7 stars

- R6.0 to the ceiling
- No insulation to the floors
- R2.5 to walls
- Timber windows to North and South, uPVC to remainder

Option 4 - Star rating: 7.2 stars

- R6.0 to the ceiling
- R2.5 to the floor
- R2.5 to walls (e.g. https://enviroflex.com.au/wall-insulation/ )
- Timber windows to North and South, uPVC to remainder

For this project we chose to proceed with Option 3 as there wasn’t enough room under the floor to install insulation.

• What other questions should I be asking you?

  • Where can people experience a Passive House?
    International Passive House Open Day is on June 28th-30th this year and gives the public an opportunity to learn and experience Passive Houses. You can learn more at the Australian Passivhaus Association website.

  • Are there any risks to improving energy efficiency?
    Condensation can be a risk if there is not enough ventilation inside a building. People, plumbing, appliances, and household plants all help to increase the moisture content of our homes. When that water vapour hits a cold surface it’s likely to condense. This is one of the reasons why it’s important to upgrade your windows and why homes that are highly sealed (5ACH or less) are required to have mechanical ventilation solutions.
    Lunos provide heat recovery extraction fan systems.

  • Where can people learn more about energy efficiency for their home renovations and new builds?
    There are some great resources online including:
    - Lighthouse in Canberra have some great casestudies online https://www.lighthouseteam.com.au/case-studies/proof-that-retrofit-measures-work
    - As do Cooee Architecture https://www.cooeearchitecture.com.au/resources/optimise
    - The Australian Passivhaus Institute website https://www.passivhausassociation.com.au/passivhaus-fundamentals
    - YourHome.Gov.Au https://www.yourhome.gov.au/passive-design/insulation
    - Sustainable Builders Alliance - Thermal Performance Checklist https://www.thesba.com.au/roadmap/performance-construction
    - My Efficient Electric Home https://www.facebook.com/groups/MyEfficientElectricHome
    
    Whisker Architecture will also be publishing more of our case studies on our website in coming months.