Deep Energy Retrofit: Design and Planning Lessons Learned
Planning a Deep Energy Retrofit is complex and requires more than just an EnerGuide report. Identifying the necessary retrofits along with the homeowner’s priorities creates a unique pathway to a high performance, low carbon home. Planning starts with an initial assessment by an energy advisor as well as detailed discussion of the needs and wants of the homeowner and their budget for the project.
To begin, check the viability of the project based on site and home conditions. For example, a simple roof to install solar is a feature that would support the success of a DER, while a hazard such as asbestos can hinder a project. Use the following as a guide to consider the viability of the home for a DER:
· Unlikely to be re-developed and not zoned for higher density
· Built prior to 1980
· Simple house shape
· Older exterior finishing in need of replacement and updates
· Simple roof shape with good access to solar
· Side yards allow for 8” additional insulation
· No recent major upgrades or renovations
· No structural damage or water intrusion
· Few or no hazards (asbestos, vermiculite, lead, poor electrical, poly-b piping)
That initial assessment must consider:
· Homeowner needs
· Maintenance priorities
· Unsafe conditions
· Future maintenance
· Energy consumption and uses
· Energy source
· Solar availability
· Occupant health and comfort
· Aging in place needs
· Aesthetics and resale-ability
Careful planning is needed when breaking up your DER into phases. This supports the end goal by allowing for proper transitions between scopes so that future work is not delayed, and current work is not wasted. Think ahead!
While detailed planning is important, details are not. It is said that no plan survives contact with the enemy, and in the case of renovations, the enemies are time, budget, and quality. It is important to be flexible while remaining focused on the goals. This project really underscored the value of the planning process, which allowed us to remain certain of our goals and priorities and enabled us to adapt to meet them when changes had to be made due to budget, product availability, and unexpected existing conditions.
The planning stage should result in:
1. Clearly defined and recorded scope of work
This is often a set of preliminary drawings that detail the proposed changes and needs. It is important to note that the home will be occupied during a DER, thus careful planning to ensure occupant health and safety is a priority. While precise construction details proved unnecessary, clear indication of all systems and changes were critical including:
· Air barrier system, its materials, connection, and transitions
· Electrical service and new wiring runs
· Mechanical changes, location, and general duct run locations
· Window sizing and hinge direction
· Colour and trim of new finishes
· Roof changes or extensions
The complexity of a DER necessitates high levels of coordination due to the multiple small scopes of work. A versatile construction team that can complete multiple tasks instead of needing to call in different professionals for a couple of hours of work will save time, money, and scheduling headaches.
2. Confirmation of permitting requirements
While many renovations do not require permits, a DER usually will. The addition of new equipment (e.g., HRV/ventilation), new windows, or a change in siding can result in the need for building permits and individual electrical and mechanical permits. Create a dialogue with the code inspectors to ensure the plans will be compliant. For example, when adding additional attic insulation or additional roof overhang length, pay attention to soffit and roof venting requirements.
3. Energy, cost, and carbon savings for each upgrade
It was important that the project team knew the performance of each improvement individually and how they fit together in steps or phases. As construction progressed and substitutions or budget constraints arose, being able to reference performance metrics and run alternatives with the energy advisor was vital.
4. Budget for construction
The planning stage isn’t really done until a complete budget has been prepared and approved. Plans and modeling must always be compared against real costs. The budget is an important final step in the planning process.
It is probable that the DER will be undertaken in two or more stages due to budgetary constraints. Planning for multiple stages will prevent previously installed systems/envelopes from covering up connections or future improvement areas; for example, if solar is planned for future installation, the conduit should be installed prior to envelope improvements; structural components of the roof should be fixed before adding ceiling insulation.
Always remember that initial planning is just that — initial. Having an energy advisor involved from the beginning allows for assumptions to be verified and qualified. For example, our initial review took place in early March and the roof seemed to have suitable solar availability. A detailed 3D study provided by the solar installer showed it to be much more shaded than originally anticipated. As a result, planned solar was relocated, and the performance of the system was improved.
Energy and carbon emission savings must be tracked and planned around. Not all changes save carbon emissions — many increase carbon even when they are very energy efficient. The goal is to find changes that save carbon, energy, and energy cost. Conveniently, our research showed energy cost and carbon savings to be closely aligned because gas in Alberta is currently cheap and has lower carbon emissions than electricity from the grid. Thus, saving or renewably generating electricity became our first priority.
The figure below shows one of the optimizations for one house. This graph shows the difference between upgrades 1–5 and the original house (base), and the effect these upgrades have on the total energy cost and energy consumption (net gigajoules of energy per year). Optimization runs provided the rationale for final decisions during the planning stage.
The homeowner, builder, and energy advisor must always think of the house as a system, looking for the interconnected nature of our home systems and how they will be affected by the renovation. For example, changing windows can cause overheating; improved air tightness without adding ventilation can cause humidity and air quality issues; and adding insulation can trap moisture if not constructed correctly.
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.