We talk a lot about the characteristics of a high performance house, here at Blue House Energy. But they’re hard to achieve if they’re not addressed in everything from the design approach to the specifications that are handed off to skilled crews.
Often, houses do not perform optimally or even as predicted by code requirements. This is due in large part to the evolution of residential construction where:
- Houses are typically field assembled
- Houses are built on a component-based approach with separate trades responsible for different pieces of the house
- No consistent process is used to identify problems or correct them.
A high performance process for building high performance houses has 3 key characteristics:
- Integrated Design Process (IDP)
- Construction Quality Management
- Commissioning
The best practice for building a high performance house is to make all the decisions about energy conservation measures during the design stage. This is the least expensive and most cost-effective part of the process. Decisions can be revisited based on energy modelling and costing before construction begins. This results in a package that works for the builder and for the homeowner.
The next best time to ensure the success of energy conservation measures is during the build.
1. Integrated Design Process (IDP) for home builders and renovators
There are six primary goals and/or features to focus on at the design stage:
- Control Air Leakage
- Increase Insulation Levels
- Minimize Thermal Bridging
- Place/Size Doors and Windows Strategically
- Provide Balanced Mechanical Ventilation
- Right-size Space Conditioning and DHW Equipment
When moving towards high performance targets, builders and developers can benefit greatly by incorporating an integrated design approach into their processes. Integrated design places a great deal of importance on building science, energy modelling, and proper costing data. Some of the areas of focus that specialists add to an integrated design process are: building design sustainability structural engineering HVAC systems lifecycle costing universal design; or building information modelling (BIM). The conventional approach is to ‘silo’ these specialties, but integrated design brings the whole team together.
An integrated design approach is important when working towards successful high performance projects, as each specialist brings specific skills and perspectives to the table. The goal of integrated design is to improve and streamline the construction process, saving time and money, but also to provide quality, comfort, and improved environmental profile for the whole lifecycle of the building.
An integrated design process is driven by the project leader. There must be a commitment from the lead to bring together the multiple disciplines in a series of steps that can provide an orderly flow to dialogue and participation. This type of process must have buy-in from all members of the design and delivery team to be successful, as the opportunities to make changes to the design and construction are most cost-effective in the first stages of design.
CMHC created a guide to integrated design for use in large construction projects that incorporate green building practices. Much of it is relevant to Part 9 construction, especially for those working with large developers and high-volume builders.
CACEA (the Canadian Association of Consulting Energy Advisors) has a pilot IDP training program for high performance houses.
2. Construction Quality Management: designed in BEFORE the building starts
Air, heat, and moisture flows all affect occupant safety, health, and comfort, as well as building durability. If a component is installed incorrectly, or if a component is modified by the occupants or renovator, or when it degrades over time, there is an impact on whole-house performance and the occupants because of changes to the air, heat, and moisture flows.
On the path to high performance housing, construction quality management becomes one of the keys to success in project management and project delivery. Good construction quality management can reduce the number of mistakes and reworks in a project. This can help projects come in on time and budget, and helps contractors maintain good relationships and their reputations.
In addition to construction quality management, the success of a project depends on the capacity of construction crews and sub-trades to carry out the work. This requires continuous training and skills improvement as well as keeping up to date with current technologies, materials, and building science. How well the insulation and air barrier are installed, for instance, is reflected directly in the results of performance tests like blower doors and thermal imaging.
Quantifying how well a house or building performs is done through metrics. Metrics are ways to measure, assess, compare, and track performance or production. There are three areas where metrics can be applied to commissioning a safe, healthy, comfortable, and affordable house that has a minimal adverse impact on the external environment:
Energy Performance Metrics (fuel consumption, operating costs, peak demand)
Indoor Environment Metrics (indoor air quality, comfort)
Durability Metrics (material degradation, maintenance costs)
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3. Commissioning: not just for big buildings!
A house is a complex system. On large commercial and institutional construction projects, a "commissioning" process is administered by an independent third party: the Commissioning Authority. This third-party structure means that the Commissioning Authority stays neutral and avoids conflicts of interest. Commissioning ensures that all systems and components are designed, installed, tested, operated, and maintained according to the operational requirements of the owner or client.
Commissioning is part of a quality management program that can help improve a builder's bottom line. It can also help a construction business identify potential improvements to new build or renovation processes. The cost of commissioning can be reduced if it is combined with other programs or the quality management process. Integrating commissioning at the start of the construction process is important to avoid scheduling conflicts and unnecessary cost.
Occupant health, safety, and comfort is impacted directly by the dynamic relationship between all of the components that make up the house. Being able to rely on a broadly used, standardized commissioning process for houses would be an excellent way to make the right decisions during the design phase of a build. Unfortunately, this is not typical industry practice, although various programs and some local building codes do provide some quality management. As we move towards high-performance housing, a standardized commissioning phase that is specific to either new or existing houses will ensure building performance. Commissioning must include diagnostic and performance testing on ventilation, space conditioning, and distribution systems.
A whole house commissioning process should account for both energy and non-energy opportunities for improving building performance, related to both the building envelope and the HVAC systems, including:
- Insulation levels and installation quality
- Airtightness
- Moisture levels
- Windows
- Space conditioning distribution strategies
- Combustion appliance backdrafting with spillage
- Indoor Air Quality
- Appliances
Responsible builders want to ensure building performance even in the absence of a standardized commissioning process. The critical first step is ensuring you understand the control layers and the various approaches to wall, ceiling, and floor assemblies. Understanding how high performance assemblies impact first costs for construction or renovation is a vital element in creating a successful project.
Home energy advisors, home inspectors, auditors, and weatherization contractors offer processes and services that can help builders succeed in high performance construction. Consulting an Energy Advisor in the design stage for any home is the first step. Using software to model the energy use of the building, an Energy Advisor can show you a variety of options that ensure building performance and can help you meet an energy reduction target.
