- Building science
- Building energy use
- Indoor environmental quality
- Thermal comfort
- Energy modeling
- Building environmental monitoring
- Building retrofits
- Occupant behavior
- Low-energy buildings
Current Research Projects
Assessing the impact of energy retrofit strategies for contemporary and post-war MURBs
Project Lead: Helen Stopps
Project Sponsors: ecobee, The Atmospheric Fund, NSERC
This project will employ strategies such as energy submetering, indoor environment monitoring, air leakage testing and resident surveys to investigate the impact of energy retrofit strategies for post-war and contemporary MURBs.
For the contemporary MURBs, this project is the first ever field-based study of smart thermostat performance in MURBs. It has included installation of smart thermostats in over 50 suites in two new condominium buildings. The operating algorithm will switch smart features on and off throughout a one-year monitoring period to gather baseline and smart thermostat performance data in tandem to control for occupant behavior differences between suites.
For the post-war MURBs, this project employs air leakage testing to assess changes to the leakage area of each suite envelope and interior partitions before and after two major retrofits: over-cladding and compartmentalization. This is the first study to directly compare the effectiveness of these two retrofit strategies through a comprehensive assessment of uncontrolled air flow.
Together these two project parts will provide essential resident feedback and performance data to prove the energy and GHG reduction potential of these retrofit strategies in the two most important GTHA MURB typologies.
A Crowd-Sourced Control Strategy for the Retrofit of Post-War Multi-Unit Residential Building Heating Systems
Project Lead: Jamie Fine
This project investigates the use of a crowd-sourced HVAC control strategy for the retrofit of space heating systems in post-war multi-unit residential buildings (MURBs). Typically, post-war MURBs do not have in-suite temperature control and each suite must be retrofit with a thermostatic valve to provide this control to residents. However, at a quoted cost of $825 to $1,400 per valve, this strategy is cost-prohibitive for mass adoption. To alleviate this issue, a crowd-sourced control strategy that allows occupants to use smartphones, or similar devices, to vote if they are too warm or too cold is being investigated. This approach allows for suite control to be grouped, thereby reducing the number of valves required for the retrofit, and cost of the retrofit.
To date, field data has been collected from a case study building in Toronto, Canada, which was used to develop and validate a 320-suite EnergyPlus simulation model. Using this tool, a variety of suite grouping options, including grouping by exposure direction, suite floorplan, and by combining floors, were tested to determine an optimized design.
Using this model, the retrofit and grouping strategies were tested, and the energy consumption and temperature profiles throughout the building were determined. Combined with a payback analysis, the results show that the optimal grouping strategy for the case study building occurred when five floors were combined in each group, and a North-South exposure split was also implemented. This strategy requires a total of eight control valves, and resulted in a 17% reduction in space heating energy consumption, an 82% reduction in overheating, and a payback period 3.3 years. These results compare favourably to the typical strategy of installing one valve per suite, which requires 320 control valves and resulted in a 26% reduction in space heating energy consumption, a 93% reduction in overheating, and a payback period 27 years. These findings demonstrate that using this novel control method can be an effective way of improving the performance of post-war MURBS. Future work will include refining the occupant vote generation algorithm in the simulation, development of the software needed to implement this control strategy, and a pilot project in Ontario, Canada, to further investigate the effectiveness of this strategy.
Characterizing Acoustic Comfort in Multi-Unit Residential Buildings
Project Lead: Maedot Andargie (Co-supervised with Dr. Liam O’Brien, Civil and Environmental Engineering, Carlton University)
Noise in residential buildings is a major concern due to the behavioral, mental and physical health impacts it can have on occupants. Noise exposure can cause annoyance, interference with daily activities and sleep disturbance. Such effects have been linked with changes in social behavior, mental health issues and increased stress levels which can lead to cardiovascular diseases. The main objective of this research is to quantify a noise level limit for acoustic comfort in MURBs and provide design guidelines or best practices for new MURB design. The research will specifically look at two metrics: annoyance and interference with activities, such as communication, relaxation, work, and sleep. A field study will be carried out where acoustic conditions and occupants’ comfort levels will be monitored simultaneously.
Assessing Window Design Strategies for Thermal Comfort
Project Lead: Shengbo Zhang (Co-supervised with Dr. Liam O’Brien, Civil and Environmental Engineering, Carleton University)
This project investigates the impact of different window design strategies on thermal comfort in contemporary condominium buildings. This study is being carried out using the energy modelling software EnergyPlus, and the thermal comfort assessment tool Ladybug. Preliminary modeling have identified that the high window-to-wall ratio featured in many of Toronto’s contemporary condominium buildings has a significant impact on building indoor environmental quality. Large glazing ratios introduce excessive solar radiation, draft, and infrared heating, which deteriorates indoor thermal comfort. Future work will include the use of machine learning algorithms to identify correlations between different window design decisions, and the effects that they have on indoor thermal comfort levels. These correlations will then be used to determine an optimal window design as a function of specific indoor design parameters, from the perspective of thermal comfort.
Characterizing Inter-Zonal Air Tightness of Newly-Constructed MURBs
Project Sponsor: ASHRAE
Proper control of inter-zonal air flows in multi-unit residential buildings (MURBs) can improve fire safety; reduce unwanted transfer of odours and pollutants between suites; reduce sound and pest transmission; and improve the control and distribution of ventilation air. Unfortunately, most air-tightness efforts for new construction in MURBs have historically focused on exterior air-tightness. In addition, the existing test methods for measuring inter-zonal air-tightness are expensive, logistically difficult to complete and disruptive to occupants. As a result, existing data on inter-zonal air-tightness are limited. In the absence of MURB-specific data, many existing standards and guidelines have been adapted using data from single-family and commercial buildings, which vary significantly from MURBs in both level of compartmentalization and construction.
The primary goal of this research is to quantify the “typical” level of inter-zonal air flows in MURBs. Test buildings will consist of contemporary, high-rise MURBs in Toronto and Vancouver. The results of this research will be used to establish achievable levels of inter-zonal air-tightness that can be incorporated into standards and guidelines. The data will also be used to assess the efficacy of different air-sealing techniques and measures. A tertiary objective of this research will be to develop and refine easy-to-implement, cost-effective measurement techniques that can be used to measure inter-zonal air flows in occupied buildings. This research will benefit stakeholders at multiple levels, including policy makers, engineers, architects, contractors and building owners/developers, and will also help to improve building performance.
Assessing the Impacts of Climate Change on Energy Use and Retrofit Potential of Buildings at U of T
Project Lead: Jia Zhe (Joey) Liu
This project determines how a changing climate will impact the performance of buildings at U of T and identify ways in which these buildings should be retrofit to improve climate resilience. Energy models of representative buildings on the U of T St. George campus are carried out using the energy modelling software EnergyPlus with current weather files and are calibrated using the collected energy data and indoor environmental data from building monitoring systems. Future weather files will be used on the calibrated model to analyze how buildings respond in terms of cooling and heating energy use and further develop potential retrofit strategies.
Development of a Parallel Flow based Analysis Method for a Solar Chimney Ventilation System in High-Rise Buildings
Project Lead: Jamie Fine
With the urban population expected to increase in the future, cities in hot climates with poor electricity infrastructure may have trouble meeting cooling demands. Natural ventilation solutions may help to offset the electricity required to cool and ventilate a building, therefore reducing energy required from the grid while ensuring a safe and comfortable environment for its inhabitants. A solar chimney is one method of natural ventilation. It uses solar energy to heat air in a vertical duct, which then rises due to the stack effect. This draws stale air out of the building and brings fresh air in.
There is a lack of a simple, reliable analysis method to find the various flow rates through each floor of the building, taking the efficiency and performance of the solar collector into consideration. This project aims to develop a method to quantify the airflow a solar collector can generate. The analysis was developed using a parallel flow network with the solar generated pressure modeled as a pump to find the flow rates through each floor as a function of the number of floors, the solar chimney height, and the duct geometry, showing initial feasibility. In order to validate the analysis method, a CFD model was developed. Future work will include comparing CFD results to the analysis results and to other solar chimney studies, as well as the development of an experimental model.
Exploring the Impact of In-suite IEQ and Controls on Occupant Behaviour and Wellbeing in MURBs
Project Lead: Yuan Cao
Project Partner: CityHousing Hamilton
Research indicates that occupants’ behavior and wellbeing are impacted by the extent of control over building systems and various IEQ factors, including thermal, lighting, acoustic and air quality. However, existing studies in this area mainly focused on evaluating the effects of only one or two IEQ parameters or control points over building system on occupants’ behaviour and wellbeing, and the majority of the studies were conducted in commercial or institutional buildings.
The main objective of this research is to provide a comprehensive evaluation on the impacts of multiple IEQ factors and controls on occupant behavior and wellbeing in residential suites by using a combination of both qualitative and quantitative approaches. Occupants’ perceptions of their subjective wellbeing as well as their interactions with building systems will be collected through surveys, interviews and photovoice practices. The targeted in-suite IEQ parameters include temperature, relative humidity, illuminance levels, sound pressure levels, occupancy status, PM2.5, CO2, and TVOCs will be monitored continuously through an integrated IEQ sensor package. This research is a subset of the Practicing Wellbeing in the Built Environment project, which is an interdisciplinary collaborative research between the Department of Civil Engineering, the School of the Environment and the Daniels Faculty of Architecture, Landscape and Design at the University of Toronto.
Completed Research Projects
Development of a Direct-to-Suite Ventilation System for Multi-Unit Residential Building Retrofits
Project Lead: Xinxiu Tian
Post-war buildings are typically ventilated using a centralized make-up air unit (MAU), which is intended to positively pressurize the common building corridors and provide ventilation air to suites through door undercuts. Overcladding retrofits for these buildings are gaining popularity as they offer improved comfort and energy efficiency. However, by improving building air tightness and insulation levels, the pressurized corridor ventilation strategy is becoming insufficient. This shift in ventilation needs has created a new retrofit market for in-suite ventilation strategies designed for retrofit applications. The BEIE Lab has partnered with Nu-Air Ventilation Systems Inc. to develop a new low-profile, high-efficiency, heat/energy recovery ventilator (H/ERV).
Through this research partnership, the H/ERV unit design will be optimized with respect to air flow rate requirements for different system layouts, unit dimensions including the height-to-width ratio, thermal efficiency compared to national standards and incentive program requirements, and hardware cost to ensure acceptability by a large market share. To determine the requirements for the design, computer simulations in CONTAM that are calibrated with field data will be used. These simulations will be based on a case study building in Ontario, representing Nu-Air’s target archetype building. This process will leverage rarely collected interzonal air leakage data and air flow data derived from fan-pressurization and tracer gas testing to calibrate the airflow models. This unique approach will ensure a more realistic representation of these building types compared to existing models, to help develop the first H/ERV specifically designed for this retrofit application.
Retrofitting Postwar Multi-Unit Residential Buildings (MURBs) with Variable Refrigerant Flow (VRF) technology
Project Lead: Mostafa Abolila
MURBs are heated in winter using hydronic systems. These systems typically use one or two thermostats for the entire building, and this causes overheating in some suites in winter. To regulate temperatures, tenants open their windows as they do not have in-suite controls. This causes energy losses that are further amplified by the stack effect. Moreover, open windows in winter have an adverse effect on the tenants’ comfort.
This research aims to study the implementation of VRF technology instead of the hydronic system for HVAC systems in MURBs. The first step of the analysis is to determine the energy savings from integrating the VRF system using the energy modeling software EnergyPlus. After that, a cost analysis will be conducted to assess the feasibility of replacing hydronic systems with VRF systems.
Investigate the Impact of Passive Approaches to Reduce Overheating in Post-War Apartment Buildings
Project Lead: Claire (Cheng) Li
Post-war apartment buildings in Toronto are typically built with no central cooling system. With the increase of extreme weather length in summer, the apartment buildings experience severe overheating due to solar gain. This project will involve development of calibrated energy model of post-war apartment buildings using the energy modeling software Energy Plus, which will be used to access the energy and thermal comfort impact of passive solar shading measures. This measure will include internal and external shading and innovative window systems. By implementing the passive strategies, the indoor environment resilience in terms of thermal comfort could be improved to accommodate extreme weather conditions in summer months.
2016-2018 Development of a low-cost moisture measurement method for assessing food dryness in developing countries
Project Lead: Marina Verz Zambrano (Co-supervised with Professor Heather MacLean, Civil Engineering, University of Toronto)
To reduce moisture-related microbial growth, food is often dried. This practice is common in small farming operations in developing countries but there is a lack of cost-effective, efficient tools to assess the sufficiency of food drying in this context. Visual inspection is the most comment dryness assessment method but this is subjective and often inaccurate.
As part of the Centre for Global Engineering’s (CGEN) Public Health Diagnostics Initiative (PHDi), the goal of this project is to develop a low-cost strategy to determine whether food as been adequately dried thus preventing food spoilage. A review of existing moisture measurement methods has just been completed to evaluate their applicability and determine potential methods that can be adapted to the developing world context.
2016-2018 An Exploratory Analysis on the Effects of Wind Catchers and Solar Chimneys on Passive Cooling in MURBs
Project Lead: Wei-Chih (Jeff) Huang
As part of the Center for Global Engineering’s Initiative for Global Urban Shelter, the BEIE Lab is designing a passive cooling solution for new multi-unit residential buildings in Mumbai that will be constructed by India’s Slum Rehabilitation Authority. Passive cooling can help maintain thermal comfort in buildings without the use of electricity. Specifically, the combined application of wind catchers and solar chimneys are being investigated to increase air movement at the suite level which can contribute to convective heat loss and evaporative cooling.
PMV and PPD thermal comfort indicators were used alongside local thermal comfort models to accommodate for acclimatization to local conditions. Feasibility was established through spreadsheet calculations and computational fluid dynamics and EnergyPlus are now being used to optimize the design and integration of the wind catcher and solar chimney.
2016-2017 Achieving a Low Carbon Housing Stock: An Analysis of Low-rise Residential Carbon Reduction Measures for New Construction in Ontario
Project Lead: Christina Ismailos
The Province of Ontario, as well as local jurisdictions such as the City of Toronto, have set ambitious targets for carbon reduction in the building sector. Since residential housing accounts for a major portion of Ontario’s building stock, improving construction and design of this building type is critical for meeting these targets. This study demonstrated how houses can reach net-zero carbon performance by optimizing key components in the building envelope and mechanical system. An accompanying cost analysis revealed how each carbon reducing strategy ranks in terms of capital cost per carbon mitigated on an annual basis. This technical analysis operates within a larger policy framework, wherein energy savings should be monitored to define actual progress towards the decarbonization goals.
2016-2017 Improving the Characterization of Infiltration and Natural Ventilation Parameters in Whole-Building Energy Models of Multi-Unit Residential Buildings
Project Lead: Cara Lozinsky
This project investigated strategies to reduce parameter uncertainty for infiltration and natural ventilation model inputs in whole-building energy models of MURBs. Air leakage testing was conducted to determine the component infiltration rate of windows and window-wall interfaces so that a component-weighted rather than bulk infiltration rate could be used to reduce parameter uncertainty in energy modeling. A pilot study to test various sensors for window operation monitoring was also conducted.
2015-2017 Impact of a Compartmentalization and Ventilation System Retrofit Strategy on Energy Use in High-Rise Residential Buildings
Project Lead: Matt Carlsson (Co-supervised with Professor Russell Richman, Ryerson University)
This project investigated the impact of a suite-based compartmentalization and ventilation strategy on the energy performance of a high-rise multi-unit residential building in Vancouver, B.C., using energy modeling software, EnergyPlus. The simulation results show that this retrofit could potentially reduce annual heating energy demand by 51% compared to the existing building which had already undergone a re-cladding retrofit. When this retrofit was modeled on the building in its original pre-retrofit condition, the estimated heating energy reduction was 49%. Building enclosure air-tightness improvements can potentially negatively impact air distribution in buildings with pressurized corridor ventilation systems, however the proposed retrofit should be applied in combination with, or before, an enclosure retrofit to prevent this outcome. This study demonstrated that the potential energy savings benefit of a compartmentalization and in-suite ventilation system retrofit can yield similar energy savings as compared with a cladding retrofit.