'Commissioning' is a big word that means, "making sure that the building systems and envelope assemblies are doing what they are supposed to be doing".

The process of commissioning is used often in large commercial and industrial construction projects, mainly because the size and operation of systems in those buildings are very large and quite expensive. Problems with energy use, indoor air quality and occupant comfort could turn into costly call-backs and delays in project completion.

In residential construction, commissioning of systems - HVAC, ventilation, electrical, etc.. - is a fairly new concept, though some large developers may commission the various model homes in their communities to demonstrate how their homes may perform once they are built.

Small and medium sized home construction and renovation / retrofit contractors who have trained in third-party or government energy efficiency labelling programs - R2000, Net Zero, LEED Homes, Passive House, etc.. - may be familiar with the commissioning process on a smaller scale. Some custom home builders may already have working relationships with Energy Advisors and energy labelling consultants.

The design process for new construction will normally follow building envelope requirements laid out in National and Provincial building codes - this is called building to a PRESCRIPTIVE path.

For energy efficiency focused new builds and retrofits, a designer will create a plan that addresses the 'house-as-a-system', aiming to make the building envelope assemblies and systems as thermally effective and as air-tight as possible. When this type of plan is made, the building is following a PERFORMANCE path - the building meets and exceeds code requirements, all in the name of energy efficiency.

ASSEMBLIES

From foundation to roof, the construction assemblies in new and existing buildings will have common elements:

• Structure
• Control layers - insulation, air barriers, vapour retardants / barriers, bulk moisture control materials (flashing)
• Windows and doors

The commissioning of residential assemblies will determine the impact and/or effectiveness these assemblies have in relation to the following:

• Heat loss and heat gain
• Air leakage rates
• Relative humidity inside the building

To demonstrate their effectiveness, built and retrofit assemblies need to resist the flow of heat, air and moisture to maintain interior conditions as close as possible to 21 degrees Celsius (70 degrees Fahrenheit) and approximately 65 percent relative humidity for optimal comfort in Canadian winter months.

According to energy labelling programs like Passive House and Net Zero, high performance assemblies will consider the following in order to achieve optimal effectiveness:

• Air tightness levels at or below 1 Air Change per Hour (ACH)
• Super insulation levels to approximately R40 in walls, R60 in attics - thermal depths for energy efficiency will be determined with effective heat loss calculations.
• Continuous insulation from foundation slab to roof to eliminate thermal bridges
• Triple pane, Low-E, thermal spacers and inert gas (between panes) with insulated frames and installations for windows and doors
• Drying potential on interior and exterior surfaces

HVAC and VENTILATION SYSTEMS

The mechanical systems in a residential building may be commissioned to determine how efficiently and effectively they perform in maintaining optimal temperatures and humidity for occupants. Systems may be 'right sized' or chosen based on the capacity of building envelope assemblies in resisting heat flow and maintaining air tightness.

When the target performance is modelled for new homes, or when a baseline performance is established in an existing building, the appropriate systems for heating, cooling and ventilation can be designed to accommodate.

Efficiency ratings of most HVAC and ventilation systems are quite high - in the range of 80 to 95%. This makes it important to combine these efficiencies with high-performance assemblies to get the maximum operational effectiveness and energy use reductions.

Once a new build or retrofit is complete, an Energy Advisor will perform systems testing and diagnostics with HVAC technicians, to ensure that everything is functioning properly and within the modelled performance targets.

ELECTRICAL and PLUMBING

The electrical demands of appliances and occupants must be mapped out in an energy model or retrofit plan. The design of plumbing systems must account for energy required in hot water heating and the collection of energy from drain water heat recovery.

Net Zero buildings are especially concerned with energy demand, as the ideal situation will include renewable energy systems to create a 'net zero' balance of energy consumption and energy production. This type of arrangement may be achieved with careful attention to effective assemblies and optimized mechanical systems in a building.

A bit of training may be required for building occupants, to show them how their systems operate and to help them manage their power consumption habits. For example, shutting off phantom power appliances and using clothesline drying for laundry may cut down on occupant power use.