How we prioritised home retrofit activities
In this post, we’ll walk through step 3 of a retrofit: planning what work to do, taking into account a budget, energy audit recommendations, other cosmetic/design considerations, and embodied carbon.
Importantly, this step of the overall retrofit process should really only be tackled once you’ve finished the first planning stages of setting a budget, selecting an auditor, and having the initial audit done.
Note that, in principle this step is just to decide on the intervention package that works for you, and then the following step 4 is to go get quotes from contractors. In practice however, you may end up finding out more during the quoting process, and that some things may be more or less expensive (or not even possible where you live!), so you may have to revise your plan as quotes come in. That said, you should be able to basically decide what is right for you and your house at this point – but be ready to iterate if needed.
The simple approach to prioritising
Also note that, in principle, this step should be quite easy. The Energuide report you will receive will list the top interventions you can do on the house in order of the highest impact. This means that a simple approach is to figure out what the out-of-pocket costs for each one will be after rebates (your advisor will be able to help you understand what the intervention should cost, and what rebates you should be able to get). You can then go down the list adding up the Out-of-Pocket costs until you reach 90% of you budget limit and stop there. NB Always leave 10%, because its critical to build in a contingency – “unexpected” things and costs overruns are predictable and inevitable.
In practice though, this approach may not yield the optimal package for you and your budget for a few reasons:
- Some interventions have to be implemented in a specific order or alongside other things for them to work or to qualify for rebates. You don’t want to just do 1/2 the work and not get the benefits. For instance, LightSpark has been supporting contestants in the challenge, and have reinforced how important it is to get the home envelope sufficiently sealed before deciding on the size of the heating unit you need.
- Some interventions have very high embodied carbon, meaning that the energy that went into making, shipping, operating, or disposing of the material used in the work is extremely high. Its important to balance the operational carbon savings (ie the amount you cut out on annual and life cycle usage) against the entire life cycle of the new materials being put in.
- Finally, you also want to consider the lifestyle implications of the work, both in terms of what it will mean for your family while the work is being done (can/should you be there and what is the disruption?) as well as the implications for the space after the work is done, for instance if you must (or want) to make cosmetic changes to the house at the same time.
A more robust approach to prioritising retrofit work
We found that the best way for us to think about a retrofit was to take all the potential interventions and then put them into “phases”, recognising that we need to tackle areas of the house over time, with a reasonsable budget and timelines for each. This meant the following phases:
- Immediate quick-wins that were low-cost (financially, in terms of embodied carbon, and in terms of “pain” to implement) and returning a lot of value in carbon and money effeciency.
- Short-term changes that were relatively low-cost in money and carbon, but that made significant improvements to our bills, our lifestyle once done, and to our efficiency.
- Mid-term changes that were higher cost and that we would want to tackle after completing a first round of changes, so that we didn’t take on too much at once.
- Long-term changes that were really high-cost and with long pay-back periods (in terms of money and carbon reduction) and that perhaps needed a bit more research and a feasibility study to understand financial and embodied carbon implications better in our context. These we would only tackle after everything of more immediate value was realised.
The Phases for Our House
For our house, these 4 phases/packages also fairly neatly translated into the 3 different floors of our house, with the simplest quick wins happening in the basement; the short-term wins happening on the top floor; and the medium-term wins on the main floor. This was also really helpful for us, as we need to stay living in the house, and this means that we can move around as the various levels are being worked on.
Phase 1: The Basement Basics
For our house, the quick wins phase 1 involved tackling the basement insulation and the crawl space; upgrading the heating system to a heat pump; and ensuring the overall envelope of the house through sealing for leaks. This basic package has really low up-front costs after rebates, and requires few carbon-heavy materials to implement. It will be repaid in very quickly in reduced heating bills – and we needed a new furnace anyway. But it is worth noting that it will only have small impact in terms of beautifying the house, as it is all “invisible” work.
Phase 2: The Upper Floor
This phase goes beyond the basement to the top floor, giving significant energy savings with a reasonable (*for us) budget, that will max out the potential rebates. This option adds more materials and embodied carbon (although we will select materials with low impact wherever possible). However, it further greatly reduces the carbon/money load of running the house through improved insulation and sealing upstairs, and through full electrification and upgrading of both water and air heating/cooling. The green roof will extend the life of the petrol-based materials that are on there (its a bitumen roof) by 15-20 years, meaning much lower overall carbon impact AND along with the reno’ing of the upstairs while insulating, will add a lot of beauty to our house and our lives.
Phase 3: the Main Floor
This phase will follow the basement and upstairs by adding an update to the main floor living spaces. This increases the budget/materials significantly, and will have a longer payback period in terms of efficiency savings to offset the embodied carbon of the work and the upfront costs. However, this work will really reduce operating costs, we will choose low-carbon materials, and it will beautify the house massively though updates to the kitchen and the sunroom. We definitely want to do all this, but it is out of budget for this year and will need to be started next year.
Phase 4: Net Zero
The final phase to get fully net zero will involve going beyond the house itself, and replacing the barriers/insulation to the outside, as well as replacing energy sources with the sun. This will be a big investment in embodied carbon and money, with a long payback period, and we need to do the math/research on it carefully before diving in. But it does seem worthwile, and it will be something to engage with after the first 3 phases are complete.
To summarise, the simple idea is just to pick the top interventions that fits in your budget and go from there. However, there are some subtleties to keep in mind and include in your planning:
- Mostly, the home envelope will be improved as a first step to eliminate operating energy loss from the existing system, and so that the appropriate upgrades to the mechanical heating system can be properly sized to the needs of the home. At the same time, while getting a better envelope in place is often going to be the first step, getting a perfect envelope can be a MAJOR job and chew up all your budget, and there are diminishing returns to doing more and more on the envelope. Especially if you are in a province where electricity is actually pretty green in the way its produced (for eg in Ontario/Quebec as this image from electricity maps shows), then getting switched off of gas for heating should be a top priority, once the obviously beneficial envelope interventions have been made.
- Also, there are also personal preferences and living/design factors that can influence decisions on what interventions to prioritize. For instance, in our case, we were already planning to do some work on the top floor to replace an old ceiling and put in a bathroom, so that meant it made sense to redo the insulation and sealing at the same time. And we are fortunate to not need AC in this house in the summer (given shady trees and good cross-ventilation), and we’re comfortable to do more “hyper-local” area heating in the winter (ie sweaters and space heaters), so we have less need for hyper-controlled temperature (and a completely sealed envelope) as compared to those with health problems or other preferences/needs.
- Finally, embodied carbon counts. There are no rebates for us installing a green roof, and it provides little in the way of insulation to reduce heating bills. But, beyond it being much nicer to look at from our home office and cooling the main floor in the summer, it extends the life of the bitumen roof (a petrol product) by 15-20 years, meaning much less wastage of a heavy carbon investment (and greatly reduced operating costs for the roof).
Based on the phases we set out, and based on our budget and desire to move further already, we decided that we would aim to get through phase 2 this year. Our goal for 2023 is to seal the home and insulate the basement; to install a heat pump for air and efficient heater for water; and to complement that work with a green roof and more extensive work on the upstairs insulation and sealing.
So thats what we’re planning and have kicked off, with materials purchases and contractors!! Woohoo. After that, we take a breather (and let the bank account recover) and then hopefully tackle phase 3 next year.
Next step (and next posts) is quotes, getting a greener homes loan, and then getting the work done….