Abstract
The single core Energy Recovery Ventilator (ERV) used in this study is equipped with defrost control that recirculates the exhaust indoor air, while keeps the outdoor air intake damper closed. This defrost strategy has the disadvantage of reducing the outdoor air supplied to the house, which may affect the indoor air quality. First, this paper presents new correlation-based models of supply air temperature T2 after the energy recovery core during normal and defrost operation modes based on laboratory experimental data. A pre-heating coil heats the supply air from T2 to indoor air temperature. Second, a house in Montreal (4356 HDD) is simulated as a reference using TRNSYS program. Since the program cannot simulate the operation under defrost mode, the new models are connected in TRNSYS using equation boxes. The energy use of houses at three locations in northern Canada with HDD of 8798 (Inuvik), 8888 (Kuujjuaq) and 12208 (Resolute), are also simulated, without and with ERV unit. The seasonal energy used for heating the house and pre-heating the supply air is compared with results from Montreal. Compared to the case without heat recovery, the ERV unit leads to energy savings: 24% (Montreal), 26% (Inuvik), 27% (Kuujjuaq), and 27% (Resolute). Compared to the minimum standard requirements, the outdoor airflow rate due to defrost is reduced by 4.7% (223 hours) in Montreal, 19% (1043 hours) in Inuvik, 13% (701 hours) in Kuujjuaq, and 24% (1379 hours) in Resolute.
Highlights
Reducing energy consumption in buildings plays an important role in reducing CO2 emissions since the building sector accounts for 40% of the global energy use [1]
The membrane energy exchanger (MEE) is recommended for cold climate applications because of its better performance on the frost-resistance and energy saving than other types of heat/energy exchangers applied to cold climates [5,6,7]
The main objective of this paper is to evaluate the effect of recirculation defrost in energy recovery ventilator (ERV) on: the total energy use of the house, the energy use for pre-heating outdoor air, the reliability of ERV in supplying the required outdoor air, and the effect on indoor humidity
Summary
Reducing energy consumption in buildings plays an important role in reducing CO2 emissions since the building sector accounts for 40% of the global energy use [1]. New houses with higher airtightness and energy efficiency (R-2000-certified houses) have been increasingly constructed to reduce heat losses and their energy impacts during operation [2]. To ensure air quality and thermal comfort as well as reduce energy use, finding the optimal mechanical ventilation solution is the concern in residential well-insulated buildings [3]. Energy use in ventilation systems without heat/energy recovery is significant in cold climates. To make a further reduction in energy use possible, it is essential to focus on high energy efficient ventilation and heat/energy recovery system [4]. The formation of frost in the energy recovery ventilator (ERV) is the primary concern for the operation in cold climates. The frost occurs inside a membrane-based ERV when the outdoor air temperature is between -8°C and -12°C. The thermal efficiency of the unit diminishes, and the unit can be damaged if no measurements are taken to remove the frost [8,9,10]
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