Monitoring and Evaluation of Nearly-Zero Energy House (NZEH) with Hybrid HVAC for Cold Climate – Canada

Abstract

A Nearly Zero Energy Home (NZEH) in Strathroy, Ontario, Canada was monitored and studied to evaluate its performance for both heating and cooling seasons. The house is a new built and is equipped with an electric-natural gas hybrid spacing heating system. A high efficiency natural gas furnace and an electric air source heat pump (ASHP) were coupled to meet the space heating demand of the house. The house also benefits from on-site renewable energy generation (solar PV). The original system was controlled by a simple switch over thermostat that drives furnace or ASHP based on the outdoor temperature as a single decision-making factor. The system then was upgraded with a cloud based Smart Dual Fuel Switching System (SDFSS) controller that considers time-of-use (TOU) pricing, fuel cost, weather forecast, and equipment efficiencies and capacities. This multi-variable decision-making process defines an optimal schedule for the hybrid system to run more efficiently and more economically. A detailed monitoring system, including sensors, meters, and data acquisition system, was installed to collect all required information at a 2-minute interval. The furnace and ASHP were studied separately to verify their capacities and efficiencies. Then the overall hybrid system and its controller were monitored to identify its effectiveness. A complete model of the house and the hybrid system were developed and validated with experimental data. Thereafter, the system was run by the SDFSS controller. All of these scenarios were compared against each other and benchmarked. In addition, the factors affect indoor air quality (IAQ) were studied in detail. The preliminary result has shown that SDFSS controller provides a cost effective, feasible, cleaner and healthier IAQ options to run the hybrid system in a NZEH.