Part 3 — Construction Lessons Learned
Part 1 — Project Kick Off: What is a Deep Energy Retrofit (DER)
Part 2 — Deep Energy Retrofit: Design and Planning Lessons Learned
Planning a deep energy retrofit has proven more challenging than anticipated in some ways, but easier in others. Completing three deep energy retrofits concurrently provided valuable project knowledge. While construction projects will always vary, we found that some of the challenges we encountered were consistent across these DERs. We also saw consistency in the timelines for these projects. Major construction lasted about three months on all three projects. There was variation in the minor work, with some starting early and some finishing work continuing slowly. Adding the sweat equity that the homeowners put in, such as painting, the full project timelines were six to nine months.
While each project utilized an exterior insulation and air sealing approach that allowed families to stay in place during the renovation, these are not minor renovations and life is certainly disrupted during that period. Careful planning helps mitigate and prepare for the disruptions, but it was easy to underestimate the impact on daily routines. Notable challenges included:
· Yards and exteriors of the homes quickly became needed for construction staging; you will lose access during the renovation, and some remediation (fixing the lawn) will be required.
· Safety during construction is an important consideration and must be managed by your contractor and trades. Ensuring that the home always has safe egress in an emergency, especially from bedrooms, that the yard is safe from construction hazards (such as nails), and that all work is conducted safely is a large part of the challenge. A safety plan and clear expectations are needed early on.
· Sometimes it is best to move out, even just for a portion of the renovation. Project 3 had the most interior work with the bathroom and kitchen undergoing renovation during the project. This did require the family to temporarily relocate for several weeks so work could proceed efficiently, and safely.
Here are the four key takeaways from the lessons we learned during construction phase:
- Project Viability
Some houses are MUCH easier to retrofit than others, and some criteria were identified as being of more importance. This challenged was recognized in the lessons learned from the design and planning of the deep energy retrofits, but was fully realized during construction. A project viability checklist was conducted for each home, identifying nine key points. Of these points the house size, height, and previous upgrades added considerable complexity to the DER process. Additionally, phasing of the retrofits was a challenge for the DER.
See the following project viability table of the three case study projects. Project 3 checked off all the project viability boxes.
2. Make it Right
As we dug into the construction of these projects, an ultimate golden rule for DERs emerged: if you’re going to touch it, make it right. This should be a golden rule for all construction but let’s look at its impact on retrofits: if your renovation is going to involve something like the wall envelope by adding new siding, it is worth renovating the entire assembly to future standards, not just to the 1.5 inches of insulation needed to meet today’s code. This will bring the wall to the ideal R-30 effective range so your home is ready for the higher standards that will be implemented in 2050. Anything less will lock in inefficiency for the life of that work, which will be at least 25 years.
If making it right doesn’t fit the budget, don’t touch it. It is hard to learn that you don’t have the budget to do everything you wanted, but don’t take a shortcut and lock in poor performance with half measures. Instead, maintain the current assembly, plan for future upgrades with the correct transitions, and start saving.
Assessing the effectiveness of DERs in the final analysis of this project, we were able to show that in many areas, half-measures were ineffective. You end up paying too much for too little in energy savings if you renovate to code minimum levels. Finding the most cost-effective approach is important but there are other factors that are not energy-based to consider. For example, an Exterior Insulation Finish System (EFIS) used by Project 2 appeared to be the most effective wall system, but what if you don’t like the EFIS look for your home and want a different siding? In this example, other approaches are nearly as good for energy savings and allow other requirements to be met. Another non-energy-based factor to consider is cost. The effectiveness of adding solar production to a home, generating energy rather than conserving it, ranged enormously between the projects. Many factors play a role in determining solar eligibility and must be carefully analyzed, such as roof complexity, facing direction, and local shading.
See the following graphs for an illustration of the effectiveness of other factors compared to energy savings. Figures 1 and 2 are from our Pathway to Net Zero final report. Figure 1 compares the cost of construction for an equivalent amount of energy saved for four different wall assembly upgrades, along with a solar array for our third project. As you can see, the EFIS assembly had the lowest cost per GJ of energy saved, but the solar installation came in a close second. If there are factors other than energy that need to be considered (e.g., cost or appearance), analyzing all your options is critical.
Figure 2 shows the cost for energy effectiveness of a solar array compared to a wall upgrade. As you can see, for some projects it would make more sense to install solar rather than upgrade exterior walls while for other projects the inverse is true.
3. Stay Flexible
Adding to the golden rule, another key to a successful retrofit is to stay flexible. Many upgrades start with grand ideas that would achieve an ideal final product. While it’s important for DERs to have these high-performance metrics, it may not be feasible to complete all your goals in one step. Plan for these phases and build the transitions that are needed to obtain your final home.
Originally, we thought that doing a Deep Energy Retrofit in one step was the only way. This strategy included envelope, mechanical, and solar upgrades, achieving 2050 readiness in single renovation. The reality is updates to the home’s envelope and mechanical systems are large and expensive work. Most of us (our case study DER included) must break this up into a couple of steps.
You might be asking why we would recommend retrofitting in steps rather than waiting until you can afford the entire job. The answer is that carbon calculations show that upgrades that save or produce energy, even in smaller amounts, are still better than nothing. Doing something now, as long as that something is well thought out and does not impede future upgrades, is better than waiting and doing nothing.
When you project energy upgrades over the next 25 years, the accumulative carbon savings vary. As shown in Figure 3, renovating towards net zero (DER projects in yellow and blue) improves carbon savings far better than a code minimum/ typical renovation (in orange). This shows that even renovating in phases, as seen with DER project 1 (in blue), towards net zero can start saving carbon emissions now.
One of the initial benefits of a DER is that you can have a home with great comfort and performance while not having to move out during construction. Building a new infill home will have you out of your home/ renting, maybe even away from your neighborhood, for at least 10 months if not more than a year. There are also large embodied carbon savings from reusing materials (the majority of your current home) rather than demolishing to build new. Figure 4 demonstrates the carbon savings of a DER (Project 1) versus building new (semi-detached, townhome, and single-family examples).
4. Yes — Permits are Required
Permitting was touched on in the previous blog post, but misunderstanding and inconsistent enforcement of permitting requirements for renovations are common. While minor maintenance and replacement does not need a permit, each of our projects was reviewed with the City of Calgary and all were found to require Building Permits. This was due to changing the type of siding. Siding is often replaced as it ages or gets damaged, which doesn’t require a permit; however, each of our projects were changing the type of siding, which was a clear trigger for a Building Permit. We were surprised that this was the determining factor rather than adding 8 inches of insulation.
Going forward, all projects pursuing a DER should plan on obtaining a Building Permit. It is an important requirement and can save headaches down the road. A permit can also provide peace of mind to the owner and future buyers of renovated homes.
We had excellent support from the City’s Safety Code Officers during their reviews. They were interested in what we were trying to do and reviewed key areas of risk such as flashing details and mechanical ventilation. The inspections had no impact on the schedule and the costs were very low.
Additional triggers for permits for these projects included:
· Change of cladding type
· Addition of new windows (also requires a Development Permit)
· Change of window sizes or positions
· Addition of an ERV/ HRV ventilation system (Mechanical Permit)
· Change of heating or domestic hot water system (Mechanical Permit)
· Removal of gas lines (Mechanical Permit)
· Modification or addition to Electrical System (Electrical Permit)
If you would like to learn more about this project, please check out the project page on SSRIA’s website and stay tuned to our social media (LinkedIn, Facebook, Twitter, Instagram, & Blog) for more updates!
Funding for this project is provided by the Smart Sustainable Resilient Infrastructure Association (SSRIA) as part of their Green Building Technology Network (GBTN) program. SSRIA is a not-for-profit association in Alberta that is fostering collaborative and innovative solutions that can achieve a path to 40% greenhouse gas emission reductions by 2030 while positioning Canada as a global leader in the Architecture, Engineering, and Construction Industry. SSRIA also supports the growth of Alberta SMEs who are developing innovative building products and technologies and ensures the current and emerging workforce have the necessary skills to work with those innovations
