Theme 3 – Building Envelope and Energy Performance

This theme consists of 3 projects which are intended to develop innovative technologies, design methods and best practices to deliver high-performance wood buildings from a building envelope performance perspective. A longer term goal of the theme 3 research is to support the development and implementation of “net-zero energy ready” and “climate-adaptive” design of wood buildings. These projects are sub-divided into a total of 10 sub-projects. The research will include laboratory testing, field monitoring, modelling, and simulations at the material-, system-, and whole building-levels to assess performance (energy efficiency, durability, healthy indoor environment, and climate resilience).

Project T3-1 – Development of Design and Best Practice for Building Envelope Performance

The focus of this project will be on field testing of existing MT buildings and hygrothermal modelling to generate technical data that will help fill the building envelope design gaps for MT buildings. It consists of 3 sub-projects.

Sub-project T3-1-A – Hygrothermal performance of mass timber envelope systems

PI: Hua Ge, Concordia University and Cynthia Cruickshank, Carleton University

HQP: Sina Akhavan Shams

Hygrothermal modelling of 2D and 3D for wood-based assemblies, especially for MT, poses several challenges, such as the lack of proper material properties (Glass and Zelinka 2010), and reduced accuracy at high moisture levels (Wads 1994). Construction moisture is another major concern as it may affect long-term durability (McClung et al. 2014; Schmidt et al. 2019). This sub-project will tackle these issues and the expected outcomes are (1) a comprehensive material property database for wood products; (2) guidelines for hygrothermal modelling based on a stochastic approach that takes into account uncertainties in directional material properties, moisture loads and climatic conditions in MT timber buildings during construction and operation.

Sub-project T3-1-B – Field measurements of the moisture and thermal mass effects of MT

PI: Yuxiang Chen, University of Alberta and Hua Ge, Concordia University

HQP: Milan Marojevic and Himanshu Sharma

Effective thermal energy storage (thermal mass) can greatly improve thermal and energy performance of buildings and increase utilization of renewable energy (ASHRAE 2019, Heier et al. 2015). Studies have shown that the use of MT can improve energy efficiency compared to light-wood frame construction (Khavari et al. 2016; Glass and Zelinka 2010), while performing comparably to concrete structures in terms of mitigating overheating risk (Jensen et al. 2020). This sub-project aims to quantify the thermal mass effect of a MT envelope on a building’s thermal and energy performance, including the capacity to regulate indoor thermal and moisture conditions by using an outdoor test hut in Edmonton. The expected Next Generation Wood Construction Page 14 of 34 Chui, Y. H. (18138) outcome is a quantified assessment of the potential of using MT for thermal storage and moisture buffering to reduce energy consumption and improve thermal resilience of wood buildings in Canadian climates.

Sub-project T3-1-C – Field monitoring of whole building performance of mass timber buildings

PI: Phalguni Mukhopadhyaya, University of Victoria and Louis Gosselin, Laval University

HQP: TBD

While small-scale lab testing and field monitoring studies have been conducted on mid-rise and tall wood buildings in terms of hygrothermal, indoor thermal conditions, and energy performance (McClung et al. 2014; Wang 2019; Schmidt et al. 2019), to improve building designs and help develop models and best practice guides, more field data is needed. In this sub-project, a comprehensive field performance monitoring of MT buildings in different climatic regions will be carried out to monitor hygrothermal performance of building envelope, indoor environment, and energy consumption. The expected outcomes are (1) field performance data in representative Canadian regions; and (2) design recommendations to achieve durable, energy efficient, healthy and resilient mass timber buildings. The field monitoring data will be used for model validation in other sub-projects, e.g., sub-project T3-1-A.

Project T3-2 – Resilient Wood Buildings – Envelope Performance

The overall objective of the research in this project is to develop design methods that would make wood buildings more resilient from a building envelope and durability perspective under current and future environment due to climate change. It consists of four sub-projects.

Sub-project T3-2-A – Optimization of building envelope design for net-zero energy and climate resilient wood-frame buildings under projected future climates

PI: Yuyang Chen, University of Alberta

PI: Yuyang Chen, University of Alberta

In order for mid-rise and taller wood buildings to achieve net-zero energy under projected future climate conditions, their building envelopes must (1) provide optimal thermal resistance in order to reduce heat loss in the Winter and heat gain in the Summer; (2) enhance passive solar heating while providing proper solar control in the Summer; (3) support renewable energy. In this sub-project different archetype buildings located in different Canadian climate zones will be evaluated. The expected outcomes are optimal design solutions that meet both net-zero energy and durability requirements for future climates, while not compromising structural performance. Given the need for design optimization, this sub-project will involve collaborators from Theme 1 (Chui) and Theme 4 (Al-Hussein), both from UAlberta.

Sub-project T3-2-B – Mitigating overheating risk in wood buildings under current and future climates

PI: Hua Ge, Concordia University and  Leon Wang, Concordia University

HQP: Zahra Salehí

This sub-project will evaluate the overheating risks in wood-frame buildings built to the current energy codes and the proposed NZER standard under current and projected future climates. With the increased frequency of “heatwaves” and projected rising temperatures, energy-efficient buildings designed to reduce energy consumption for space heating in Canada may be subject to a risk of overheating in warm seasons (Baba and Ge 2019; Laouadi et al. 2020). The expected outcomes of this sub-project are design and operational strategies, such as natural ventilation, night-time cooling, solar control through passive solar design and dynamic shading, thermal mass, and pre-cooling to reduce overheating risks in wood- frame multi-unit residential buildings, located in different Canadian climate zones.

Sub-project T3-2-C – Improved resilience against water damage caused by indoor leakage

PI: Phalguni Mukhopadhyaya, University of Victoria

HQP: TBD

While most performance issues for mid-rise wood-frame construction related to structural, fire, and energy performances have been addressed, potential water damage due to accidental indoor water leakage has not been investigated in depth and remains a concern for owners and insurance companies (Ni and Popovski 2015; Hodgin 2018). This sub-project will focus on identifying potential sources of indoor water leaks, their impacts, and measures that can be taken to improve the resilience of wood- frame construction against such risks. The expected outcomes are effective moisture management guidelines for dealing with indoor leaks to prevent damage to wood components.

Sub-project T3-2-D – Energy-efficient ventilation design for healthy indoor environment in wood buildings

PI: Leon Wang,  Concordia University

HQP: Fuad Baba

Air-tight energy efficient buildings rely on mechanical ventilation to ensure indoor air quality (IAQ), while higher ventilation rates may be required to deal with emergencies such as COVID-19 (Lewis 2021). Maintaining a safe, healthy, and comfortable indoor environment while limiting energy consumption has become particularly important for all residential buildings (Memmott et al. 2021). This sub-project aims to develop ventilation strategies to achieve optimal IAQ in energy-efficient wood buildings. The expected outcomes are design tools and energy-efficient ventilation design and operational strategies and guidelines for achieving healthy wood buildings.

Project T3-3 Innovative Building Technologies for High-performance Wood Buildings

The two sub-projects under this project explore a few innovative technologies, including energy retrofitting technologies, including the use of bio-based insulation, for existing buildings using wood assembly and advanced sensors for field monitoring work.

Sub-project T3-3-A – Prefabricated, wood-based multi-function envelope systems for energy retrofitting

PI: Cynthia Cruickshank, Carleton University

HQP: John Dikeos

Deep energy retrofitting of existing buildings has become critically important as a means of reducing energy consumption and carbon emissions from the built environment. It also makes older buildings more comfortable, durable, and climate-resilient. One of the most effective approaches to deep energy retrofitting is exterior retrofitting carried out by adding prefabricated panels to the exterior walls and roof to improve thermal performance. This sub-project will examine the use of light-wood or MT assemblies for exterior energy retrofits. Conventional light-wood-frame panels and innovative wood fibre insulation-based panels will be used for low- and mid-rise wood buildings, while CLT-based assemblies may be applied to non-wood buildings up to 12 storeys. The expected outcomes are a comprehensive strategy and innovative assembly designs with wood-based, low-carbon products for the exterior envelope energy retrofit of existing buildings that has the potential to be scaled up for existing buildings, including non-wood structures. The work will also facilitate and expand the use of innovative bio- products, including wood fibre insulation, in North America. Collaborators from Theme 1 (Erochko) and Theme 2 (Hajiloo) will be part of the project team (all from CarletonU).

Sub-project T3-3-B – Development of digital technology to facilitate long-term field monitoring

PI: Louis Gosselin, Laval University

HQP: TBD

Monitoring of building envelope performance of existing buildings can provide vital information in the development of models and design guidelines. However, the cost and time required to install sensors and data-logging systems for long-term monitoring are often prohibitive. This sub-project aims to develop a cost-effective, real-time system to monitor the hygrothermal state of building envelopes and indoor environmental conditions. Three novel approaches of using powerless, embedded and virtual sensors, will be developed, tested, and compared. The expected outcome will be a complete field monitoring test system, including data acquisition, storage, and transmission. The team working on this sub-project will ollaborate with the teams on sub-projects T3-1-B and T3-1-C.