Conference Agenda

For several years, industry and regulations have evaluated the ventilation systems inside buildings using a perspective approach by fixing ventilation rate requirements for each room type. After the COVID-19 pandemic, followed by the energy crisis, the community is increasingly interested in being assured of the level of Indoor Air Quality (IAQ) and energy consumption of the installed ventilation system, not only because it is the only barrier between outdoor pollution and indoor air but also because it represents 60% of building energy consumption. Two separate simulation models have been constructed to evaluate CO2, humidity, formaldehyde, PM2.5 levels and energy consumption inside individual households and multifamily buildings. Both simulation models include all the parts of the ventilation systems installed and use the performances of the products collected from the certification database. In this study, the levels of IAQ and energy consumption of single-flow and dual-flow ventilation systems have been compared in the cases of individual households and multifamily buildings. The impact of the outdoor conditions, airtight and leaky building envelopes, neighbouring environments, and the building’s wind exposure are also considered. This paper outlines the methodology used and presents the results, highlighting the differences in energy efficiency and IAQ performance between the ventilation systems.

Heat pumps are seen as the heating and cooling technologies of the future. Previous research has shown that combining heat pumps with other sources (i.e. ground coupling, waste heat etc.) could lead to heat pumps having a significant potential to decarbonize residential heating and cooling. One solution that combines heat recovery and heat pumps is exhaust air heat pumps. Despite some literature suggesting that exhaust air heat pumps underperform, there are many other studies which suggest they perform well if considered at a different boundary by incorporating heat recovery ventilation also. The other benefit of these types of systems is that they could also be used in cooling mode. Limited measured evidence exists of the benefits of heat recovery and cold recovery in such systems, these systems could be critical in a country’s renewable energy requirements. The following study presents an energy assessment of two reversible exhaust air heat pump systems with heat recovery; one is in Luxembourg, and one is in northern Italy. Results show that systems had a seasonal co-efficient of performance between 4.0 and 8.7 in heating mode, and between 3.1 and 5.1 in cooling mode. Heat recovery was seen as a key part of the performance achieved and could be a critical part of ensuring technologies are considered renewable (particularly in cooling mode). Future research should consider modelling the benefit of heat and cold recovery in reducing the demands placed on the grid, as well as considering how these technologies could be enhanced further with other hybrid options.

In North America, building owners and industry are beginning to transition to in-unit energy/heat recovery ventilation (ERV/HRV) systems over pressurized corridor ventilation systems in multi-unit residential buildings (MURBs). However, there is little empirical evidence supporting this transition due to the associated cost and complexity of field-based MURB ventilation system studies. This study analyzes measured data obtained during the winter-time in side-by-side architecturally similar apartment buildings, one relying on an in-unit ERV system and one relying on the pressurized corridor ventilation system for outdoor air delivery to units. The data analyzed includes ventilation system energy use and airflow rates, as well as the indoor air quality (IAQ) and thermal conditions in 34 units. Measurements were obtained in units distributed across 6 floors of the two buildings to allow for the influence of wind and stack effect on the ventilation systems to be evaluated. The findings from this study contribute measurements to support the industry shift toward a decentralized (in-unit) ERV/HRV system and methods for improving system performance. Future work will analyze measured data over an entire year, allowing for the influence of stack effect on ventilation system performance to be investigated in detail.