The inconvenient truth about "sustainability"
Unless you're living in a lean-to in the rainforest, foraging for food, you're basically not living "sustainably" in the truest sense of the word. The very concepts of sustainability and "sustainable growth" are in themselves compromises resulting from the economic unpalatability of "limits to growth", which no-one wants to acknowledge. Even in the face of peak oil, overpopulation, food shortages and climate change, most governments still seem to be suffering under the delusion that growth rates can be maintained or increased. Two of my favourite quotes are:
"Anyone who believes exponential growth can go on forever in a finite world is either a madman or an economist."
~ Kenneth E. Boulding
"Infinite growth of material consumption in a finite world is an impossibility."
~ E. F. Schumacher
I find government policy in this area to be rather schizophrenic and nonsensical to say the least - on the one hand they finally seem to have twigged to the fact that climate change is real and serious, yet on the other hand they insist that growth (i.e. production and consumption) must be maintained at all costs and are therefore investing heavily in all the areas that contribute most to climate change (roads, mining, fossil fuels, industrial agriculture etc). WTF?!
So, I'm not sure whether "sustainable" is a word that we can, in good conscience, apply to our renovation. All I can say is that, given the society we live in and its commonly accepted (if somewhat misleading) definition of "sustainable" we're doing our best, within time and budgetary constraints, to recycle and reuse as much as we can (or replace with environmentally sensitive new options where necessary) in order to extend the life of an existing dwelling and make it much more efficient in terms of energy, water use and local food production. So, with this in mind, here's what we've done:
Passive solar design
See this Wikipedia article on passive solar design.
- Opened up previously enclosed verandahs and fanlights for better cross-ventilation
- Built additional covered verandahs or extended roof eaves to shade living areas
- Added a new back deck with skillion roof to provide shade in summer and sunlight in winter to the main living areas (see also our original idea for a true solar pergola, discarded in favour of this simpler and less costly solution)
- Moved bathroom and kitchen to southerly side of house so that living areas can benefit from sun and breezes (this also allowed us to group all the plumbing and much of the electrical conduit into 2 central walls)
- Added more northern doors and windows to catch the prevailing breezes
- Retained much of the underhouse airflow that made the "Queenslander on stumps" well-suited to this climate (i.e. we opted not to build in all of the new area made available after raising the house to legal height)
- Planning on planting a deciduous pecan nut tree to shade the front, Western wall from summer afternoon sun
- Modelled the site in 3D and performed shadow analysis for each season of the year
- Added long-lasting, stainless steel rainwater tanks totalling 28,700 litres in capacity for flushing loos, washing clothes and garden watering
- Chose water saving appliances (e.g. good star rating front-loading washing machine, dishwasher, dual flush toilets, taps with flow restrictors, efficient shower heads etc)
- Permeable driveway (TurfStone) to retain and fully utilise rainfall onsite, rather than losing it to municipal stormwater drains, where it can cause environmental problems
- Sub-surface drains surrounding the slab move excess stormwater away from the house into twin soakage pits on either side of the back yard, where water can be best taken up by fruit trees and vegetables
- Planning to add a greywater recycling system in the near future
- Early on we also investigated the possibility of installing onsite wastewater treatment (like a Biolytix or Worm Farm Waste System) but council wouldn't allow it. It's a similar bureaucratic red tape story if you want to use composting loos like the Clivus Multrum or Nature Loo when residing in council areas that already have town sewerage connected to the property.
- Increased the potential living density of the dwelling (downstairs self-contained "granny flat") without sacrificing the upstairs livability, privacy, garden space or too much underhouse airflow
- Made the downstairs bathroom wheelchair accessible
Eco sensitive and safe materials
- Reused as many of the exisiting old materials as we could (windows, doors, VJs etc)
- When new materials were necessary, we used mostly locally grown plantation timber - Araucaria (Hoop Pine)
- Eliminated use of formaldehyde containing MDF throughout - e.g. opted for solid wood (Hoop Pine + Blue Gum) kitchen and VJ internal cladding
- Used low or zero volatile organic compound (VOC) paints and finishes throughout
- Safely removed the hazardous asbestos that had been used to enclose the verandahs in the 1950s
- Unavoidable demolition and building waste (there's a frightening amount generated!) processed by Green Bins, who recycle more than 80%, thereby reducing the amount that goes to landfill
- Chose locally manufactured products when available (although this is no guarantee of lower embodied energy)
- Chose quality products made from durable materials, so that they are more likely to last and don't have to be replaced too soon or too frequently, which is also cheaper for us over the longer term
- Where new appliances were needed, we chose energy efficient models (e.g. good star rating electric induction cooktop) all powered by 100% green energy
- Added refrigerator rear ventilation to improve heat dispersal, thereby minimising energy use (i.e. we take cool air from down low and use natural convection currents to vent the hot air generated by the fridge up and out).
- Fluorescent, CFL and LED lighting throughout
- Added reflective foil and some bulk insulation (the ideal quantity, type and mix of insulation materials will vary quite a bit depending on your local climate, your home's solar orientation and type, so check with an unbiased expert before just adding a whole lot of bulk insulation, which isn't desirable in some climates as it can prevent accumulated hot air from escaping on hot, humid nights)
- Replaced old rusting roof with an efficient cool roof - Colorbond "Surfmist" (very low solar absorbance of 0.318). Just say "no" to black tile roofs!
Local food and community engagement
- Planning a permaculture garden in our yard in order to grow most of our own food
- In addition to the back yard, the extensive new verandah and deck space (permaculture 'zone zero') provides ample room for potted plants like herbs and dwarf fruit trees
- Kaja is working with council and interested community members to get a community garden established in our area
- We tracked down the sons of the original owners of the home to give them an opportunity to see the house again before it changed, and also to learn more of the history of the home, the suburb and the people from first-hand accounts
Some of the aspects where we have possibly missed the sustainability mark:
- Overengineered slab and footings - probably too much concrete and steel. We could have researched better alternatives and questioned the engineering assumptions
- We originally designed a solar pergola for the back deck, but due to the orientation of the house (which wasn't practical to change) the scale and complexity of construction made it too expensive to seriously consider. The angle of the skillion roof that we eventually opted for will still give us decent shade throughout the day in summer, yet allow sunlight to penetrate into the living area during cooler winter mornings.
- We're not sure about the long-term health effects of the glass wool insulation that is part of the refective foil under-roof blanket. Likewise for the rock wool insulation between the floors - there is some question mark about its safety.
- We tried to eliminate the use of PVC pipes feeding the rainwater tanks, but we were informed that if we used steel instead for the long horizontal suspended pipes that we needed, then they would not be able to be adequately sealed and would eventually leak or break at the join during heavy rain.
- There are probably many small details where we didn't have the time or energy to research adequately and therefore left to the discretion of our builders, however to their credit they have often suggested greener options without our having to ask because they are aware of what we're trying to do