HVACs in net zero ready homes

Sustainable Comfort: HVAC’s Critical Role in BC’s Net Zero Ready Home Construction

As British Columbia continues to lead the way in green building practices in Canada, knowledge and expertise in designing and installing efficient HVAC systems will be crucial in meeting the province’s ambitious energy and climate goals.

The BC Energy Step Code is a relatively new standard designed to help the BC government and construction industry chart a course for all new homes in the province achieving “Net Zero Ready” status by 2032. By adopting one or more steps of the standard, local governments have been empowered to increase the building performance requirements in their communities at an appropriate pace. As more cities and municipalities in British Columbia adopt the BC Energy Step Code’s ‘Step 5’, new homes will be required to be “Net Zero Energy Ready” (NZER) well before the 2032 target.

The term Net Zero Ready refers to homes that are built to achieve net zero energy consumption when a renewable energy system is installed. With the addition of a renewable energy source, such as a solar panel and/or wind turbine system that meets the designer’s specifications, your home will produce as much energy as it consumes annually. Achieving net zero involves balancing the energy your home consumes with the energy your renewable energy source produces. Meeting the requirements for “net zero readiness” focuses on the former, minimizing your home’s energy consumption.

Energy efficiency is all about reducing your home’s demand for energy. Your architect or designer, and the building contractor, will help you reduce your household’s energy consumption by selecting energy-efficient building materials, installing thick continuous insulation and triple pane windows, sealing the building envelope, eliminating thermal bridges, choosing energy-efficient HVAC systems, and incorporating smart design strategies that minimize your energy waste.

In this article, we will focus on energy-efficient HVAC (heating, ventilation, and air conditioning) systems, and their importance in minimizing your home’s energy consumption.

Key benefits of being net zero ready

As a homeowner planning a custom home, adopting the BC Energy Step Code’s Step 5 on top of the BC Building Code may sound like an imposition by local government. Helping Canada reach its 2030 Emissions Reduction Plan targets may not be your most pressing concern as you work with your designer within your home’s budget, but there are some significant advantages to building a house that is net zero ready.

Exceptional energy efficiency: Net zero ready homes are up to 80% more energy efficient than conventional homes built to the BC Building Code. This increased efficiency translates to significantly lower utility bills and energy costs.
Future-proofing: Net zero ready homes are designed to easily add renewable energy systems, like solar panels, at a future date to achieve full net zero status. You’ll be ready for your household’s future energy needs and the inevitable upgrades to energy regulations.
Exceptional comfort: Even without the renewable energy source, your net zero ready home will provide outstanding year-round draft-free comfort and even temperatures, due to superior insulation, airtight construction and advanced heating, ventilation and cooling (HVAC) systems.
Improved indoor air quality (IAQ): Airtight net zero ready homes require a mechanical ventilation system. These built-in fresh air systems reduce allergens, dust, pollen and other pollutants, creating a healthier living environment for your family.
Quieter living spaces: The superior insulation, airtightness, triple glazing and construction methods result in a home that is quieter and better protected from outside noise.
Lower maintenance costs: Net zero ready homes are built to higher standards, with advanced materials and technologies. This makes them more resistant to moisture, air leakage, and temperature fluctuations, resulting in a more durable structure. High-efficiency triple-pane windows and HVAC systems are also built to last longer and require less frequent replacement.
Higher resale value: According to Real Estate Experts, homes with a RESNET HERS® score can sell for at least 2% more. Net zero homes have HERS scores of “0”, and that rating can add 3-5% more to the value over conventional homes.
Protection against rising energy costs: The high efficiency of net zero ready homes insulates homeowners from the brunt of future increases in energy prices.
Environmental responsibility: A net zero ready home consumes up to 80% less energy than a conventional home, significantly reducing your household’s environmental footprint. The precise planning and construction methods used in building a net zero home typically result in less construction waste; and by building to higher standards with quality materials, these homes will potentially last longer, requiring less frequent renovations or replacements, which reduces waste and resource consumption.

Key HVAC components for Net Zero Ready homes

The HVAC (heating, ventilation and air conditioning) systems in your net zero ready (NZR) home will consist of a mechanical ventilation system and heat pump system to handle heating and cooling.

Heat recovery ventilators (HRVs) and energy recovery ventilators (ERVs): Heat recovery ventilators (HRV) or energy recovery ventilators (ERV) are essential components in airtight NZR homes for ensuring there is adequate ventilation while minimizing energy loss. These systems exchange fresh stale indoor air with fresh, filtered air from outside, while recovering heat (and sometimes moisture) in the process. You can enjoy a continuous supply of fresh air without significant energy penalties.

The primary difference between the two systems is that an HRV transfers heat while an ERV transfers both heat and moisture. ERVs are best suited for the colder, drier climates of BC’s interior and northern communities, while HRVs work better in the milder, more humid winters of Greater Vancouver and the Sea to Sky Corridor. If your home is expected to encounter issues with moisture and dryness, you should consider getting an ERV to help maintain the indoor relative humidity levels in your home.

High-efficiency heat pumps: Heat pumps offer homeowners an energy-efficient alternative to furnaces and air conditioners for all BC climates. Heat pumps use electricity from the power grid or your renewable energy source to transfer heat from a cool space to a warm space. This makes the warm space warmer and the cool space cooler. Heat pumps transfer heat rather than generate heat the way a traditional furnace or fireplace does.

During the cooler ‘heating season’, your heat pump system moves heat from the cool outdoors into your warm home. Then, during the hotter ‘cooling season’, your heat pump system moves heat from your house to the outdoors.

There are three main types of heat pumps:

1. Ducted air-source heat pumps (ASHP): Air-source heat pump systems are the most common, transferring heat between your house and the outside air. They provide both heating in winter and cooling in summer through the same system.

Heat pumps today can reduce your heating costs by roughly 65%, compared to baseboard resistance heaters and conventional furnaces and boilers. High-efficiency heat pumps can dehumidify more effectively than standard central air conditioners, which reduces your energy usage while providing more cooling comfort during the summer months.

The temperature is typically managed via a single central thermostat for the whole home. By using electricity instead of fossil fuels, ducted heat pumps can significantly reduce your home’s carbon footprint.

2. Ductless mini-split air-source heat pumps: For some net zero home applications mini-split systems offer unique advantages. Ductless systems can eliminate a significant amount of energy loss through potential ductwork leaks and thermal inefficiencies. Ductless systems deliver air directly to each of the zones. Many ductless mini-split systems use inverter technology, which allows the compressor to adjust its speed continuously to maintain the desired temperature, reducing energy consumption compared to systems that cycle on and off frequently.

Ductless mini-split systems provide the flexibility to heat or cool individual rooms or zones independently. These systems are particularly popular with multi-generational households, allowing family members to adjust temperature zones to suit specific needs and preferences, leading to greater comfort for everyone, while reducing energy waste. By only conditioning occupied spaces, ductless systems can also prevent energy from being wasted when certain areas of the house are unoccupied for periods.

3. Geothermal heat pumps: Ground-source or water-source geothermal heat pumps can achieve higher efficiencies by transferring heat between your home and the ground on your property, or a nearby water source. Geothermal heat pumps can cost more to install, but they have very low operating costs because they utilize relatively constant ground or water temperatures.

Geothermal heat pumps can reduce your household’s energy use by 70 – 80%, they control the humidity, and they’re robust and reliable. The size of your lot, the subsoil, the landscape, or the available water source will determine whether a geothermal heat pump is suitable for your property.

The takeaway

The role of HVAC systems in the design and construction of net zero ready custom homes in BC cannot be overstated. These systems are central to achieving the energy efficiency, comfort, and indoor air quality that define BC’s NZR homes. By leveraging advanced technologies such as HRVs or ERVs, high-efficiency heat pumps, and ductless mini-split systems, and later integrating them with a renewable energy source, you as a homeowner can create a sustainable and resilient living environment.

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