Client: Thompson Family
Location: Westboro, Ottawa, ON
Completion Date: March 2024
Services Provided: Complete Demolition, New Construction, High-Efficiency HVAC, Radiant In-Slab Heating, Instantaneous Hot Water System with Recirculation Loop
This project entailed a full demolition of the existing structure, followed by the construction of a 4000-square-foot custom home designed for high energy efficiency and occupant comfort. MNE Energy led the design and installation of advanced mechanical systems tailored to the client's needs, including a sophisticated air exchange system, radiant in-slab heating in the basement, and an instantaneous hot water system complete with a recirculation loop. The project was planned to maximize energy efficiency, improve indoor air quality, and provide enhanced comfort through a seamless integration of systems.
The integration of multiple high-performance systems presented unique challenges. The large square footage necessitated careful planning to ensure adequate airflow and ventilation while maintaining optimal energy efficiency. The radiant in-slab heating system required precise design for even heat distribution, and the instantaneous hot water system needed a recirculation loop to deliver hot water instantly throughout the extensive plumbing network. Each of these systems had to work cohesively, requiring meticulous planning and coordination.
To address these challenges, MNE Energy adopted a multi-stage design and installation approach, combining energy-efficient HVAC solutions with cutting-edge heating and water systems. The following details each phase of the construction and design process:
1. High-Efficiency Air Exchange System Design and Installation:
MNE Energy installed a high-capacity energy recovery ventilator (ERV) to handle the ventilation needs of the 4000-square-foot space. The ERV system was selected for its ability to recover both sensible and latent heat from the exhaust air. This feature conserves energy by preconditioning incoming fresh air, which is critical in Ottawa’s extreme climates. The system was designed with a variable-speed fan that adjusts the air exchange rate according to occupancy, using sensors to detect levels of indoor air pollutants, such as carbon dioxide and VOCs.
The ERV ducts were carefully routed to provide balanced ventilation throughout the home, ensuring that fresh air reaches all occupied spaces while extracting stale air from areas such as bathrooms, kitchens, and laundry rooms. Advanced filtration was incorporated into the ERV unit, using HEPA-grade filters to remove particulates from incoming air, which enhances indoor air quality. Each room received individually calculated airflow rates to ensure that ventilation is consistent, with an overall focus on maintaining a slightly positive pressure within the home. This design approach helps prevent outdoor air infiltration, contributing to lower heating and cooling loads.
2. Radiant In-Slab Heating System:
The basement heating system was designed as a radiant in-slab solution to provide gentle, consistent warmth. PEX tubing was installed in a serpentine pattern directly within the concrete slab, allowing heat to radiate upward through the floor. MNE Energy calculated the precise layout and spacing of the tubing based on the basement’s thermal load, ensuring uniform heat distribution. A high-efficiency condensing boiler was selected to supply hot water to the tubing at controlled temperatures, providing optimal performance and energy efficiency.
The system design included multiple heating zones, allowing the client to independently control temperatures in different sections of the basement. This zoned approach provides flexibility for comfort while enabling energy savings by reducing heating in areas not frequently used. To further enhance efficiency, insulation was installed beneath the slab and around the perimeter to minimize heat loss. The radiant heating system offers the added benefit of silent operation and improved air quality, as it doesn’t rely on forced air circulation. The thermal mass of the concrete slab helps to store heat, ensuring that warmth is retained even after the system cycles off.
3. Instantaneous Hot Water System with Recirculation Loop:
The hot water system includes a tankless, high-efficiency water heater, which provides on-demand hot water without the need for a storage tank. This system is particularly beneficial for larger homes, as it eliminates the standby energy losses associated with traditional water heaters. To meet the client’s requirement for immediate hot water access, MNE Energy installed a recirculation loop that continuously moves hot water through the main supply lines. This setup ensures that hot water is available at every fixture within seconds, eliminating the water waste and inconvenience of waiting for hot water.
The recirculation loop includes a demand-controlled pump, which activates when hot water is needed, directing unused hot water back to the heater rather than allowing it to cool in the pipes. The loop was designed with insulated piping to prevent heat loss and improve efficiency. Additionally, the recirculation system was programmed to run on a timer during peak usage hours and on demand at other times, minimizing energy consumption. The combination of on-demand heating and recirculation reduces water waste, conserves energy, and ensures user convenience.
4. Energy-Efficient Building Envelope and HVAC System Coordination:
To support the advanced HVAC and heating systems, the home was constructed with a high-performance building envelope that minimizes air leakage and thermal bridging. The walls were insulated to R-40, and the attic to R-60, with continuous exterior insulation to reduce heat loss. High-efficiency, triple-pane windows were installed, featuring low-emissivity coatings and argon gas fill for enhanced thermal performance.
By carefully coordinating the building envelope with the HVAC and heating systems, MNE Energy ensured that the home’s mechanical systems operate at peak efficiency. The envelope reduces the load on the heating and cooling systems, allowing the air exchange and radiant heating systems to maintain consistent indoor conditions with minimal energy input. A continuous air barrier was installed to further reduce air infiltration, which works in concert with the ERV to maintain indoor air quality and optimize energy use.
The Thompson Family’s new home in Westboro was completed within the project timeline and met all client specifications. The high-efficiency ERV provides constant fresh air, while the radiant in-slab heating delivers uniform warmth in the basement. The instantaneous hot water system with recirculation loop has proven to be exceptionally convenient, providing the family with hot water on demand while reducing water waste.
Post-construction testing demonstrated that the home’s energy consumption is over 30 percent lower than a conventional home of comparable size. The coordinated design of the building envelope, HVAC, and radiant heating systems has yielded a high level of thermal comfort, improved indoor air quality, and reduced operational costs. The client expressed satisfaction with the efficiency, comfort, and functionality of the home, particularly appreciating the energy savings and convenience offered by the integrated systems.