Advanced industrialized construction methods enable complex building components and systems to be built with high precision and quality. This manufacturing technique has an advantage to provide cost-competitive and high energy efficient building components and systems for both retrofits and new construction. This document gives an overview of the use of prefabricated panels in building Net Zero Energy Ready wood-frame multi-unit residential buildings (MURBs) in Edmonton.
Cross-laminated timber (CLT) modular construction possesses the advantages of wood, such as excellent carbon storage and thermal insulation, and of modular construction, such as considerably reduced construction period and cost as well as high productivity. This study evaluates the hygrothermal performance of CLT walls considering modular construction in future climatic conditions. Firstly, CLT walls with plywood applied to a core layer were manufactured. A mock-up of a CLT building was produced and its construction process was analyzed. Hygrothermal behavior of the CLT walls was simulated using WUFI simulation program, and the predicted results were verified against measurements obtained from the mock-up experiment. Finally, the hygrothermal performance of the CLT wall was evaluated for four types of insulation and future climate in eight cities of USA. The coefficient of variation—root mean square error (CV(RMSE))—of the temperature and relative humidity inside the ply-lam CLT wall from mock-up experiments and simulation evaluation were 6.43% and 7.02%, respectively, which met the validation criteria. Based on the hygrothermal performance, the ply-lam CLT wall with extruded polystyrene insulation was evaluated as safe from moisture problems in all the eight cities considered in this study. However, the risk of mold growth in all regions and insulation types increased under climate change with a rise of average annual temperature.
Project contact is Paulo Tabares at the Colorado School of Mines
Cross Laminated Timber (CLT) is a mass timber material that has the potential to expand the wood building market in the U.S. However, new sustainable building technologies need extensive field and numerical validation quantifying environmental and economic benefits of using CLT as a sustainable building material so it can be broadly adopted in the building community. These benefits will also be projected nationwide across the United States once state-of-the-art software is validated and will include showcasing and documenting synergies between multiple technologies in the building envelope and heating, ventilation and air conditioning (HVAC) systems. However, there are no such studies for CLT. The objective of this project is to quantify and showcase environmental and economic benefits of CLT as a sustainable building material in actual (and simulated) commercial buildings across the entire United States by doing: (1) on-site monitoring of at least four CLT buildings, (2) whole building energy model validation, (3) optimization of the performance and design for CLT buildings and (4) comparison with traditional building envelopes. This knowledge gap needs to be filled to position CLT on competitive grounds with steel and concrete and is the motivation for this study.
Project contact is Eric Wood at Morrison Hershfield
The project develops building archetypes, cost data and energy modelling to allow users to cost out mass timber buildings from basic, code-compliant buildings to high-performing, energy-efficient, low-emitting buildings. It will help quantity surveyors, designers, and other decisionmakers undertake business-case development by clarifying cost variables associated with mass-timber construction.
Project contact is Mark Fretz at the University of Oregon
University of Oregon and Oregon State University are collaborating through TallWood Design Institute (TDI) to upgrade aging, energy inefficient and seismically unprepared multifamily housing by developing a mass plywood (MPP) retrofit panel assembly that employs digital workflows and small diameter logs (down to 5") to create an economically viable energy/seismic retrofit model for the West Coast and beyond. The project has broad potential to support forested federal land management agencies and private forestry by proving a new market for small diameter logs.
The objective of this study was to assess the potential effects of climate change on the moisture performance and durability of massive timber walls on the basis of results derived from hygrothermal simulations. One-dimensional simulations were run using DELPHIN 5.9.4 for 31 consecutive years of the 15 realizations of the modeled historical (1986–2016) and future (2062–2092) climates of five cities located across Canada. For all cities, water penetration in the wall assembly was assumed to be 1% wind-driven rain, and the air changes per hour in the drainage cavity was assumed to be 10. The mold growth index on the outer layer of the cross-laminated timber panel was used to compare the moisture performance for the historical and future periods. The simulation results showed that the risk of mold growth would increase in all the cities considered. However, the relative change varied from city to city. In the cities of Ottawa, Calgary and Winnipeg, the relative change in the mold growth index was higher than in the cities of Vancouver and St. John’s. For Vancouver and St. John’s, and under the assumptions used for these simulations, the risk was already higher under the historical period. This means that the mass timber walls in these two cities could not withstand a water penetration rate of 1% wind-driven rain, as used in the simulations, with a drainage cavity of 19 mm and an air changes per hour value of 10. Additional wall designs will be explored in respect to the moisture performance, and the results of these studies will be reported in a future publication. View Full-Text
Project contact is Weichiang Pang at Clemson University
The overall goal of this project is to enable the use of cross laminated timber (CLT) to construct commercial and other non-residential buildings in High Velocity Hurricane Zone (HVHZ). The 1992 Hurricane Andrew exposed the shortcomings of existing building codes. Recognizing this shortcomings, the Florida Building Code (FBC) incorporated new enhanced provisions which specifically require that the entire building envelope, including the wall and roof systems, must be impact resistant in HVHZ. Currently, CLT is not in the database of a list of building envelope products that comply with the HVHZ standard. The specific objectives of this project are (1) to qualify PRG-320 compliance CLT panels for HVHZ standard by conducting FBC debris impact and wind pressure cyclic tests; (2) to conduct education and outreach sessions to promote the use of CLT in HVHZ, and (3) to identify possible construction projects that may utilize CLT as the building envelope and promote the use of CLT in those projects. The test results generated in this project will be used specifically to gain HVHZ building code approval.
Ventilated façades can help to reduce summer building thermal loads and, therefore, energy consumption due to air-conditioning systems thanks to the combined effect of the solar radiation reflection and the natural or forced ventilation into the cavity. The evaluation of ventilated façades behavior and performance is complex and requires a complete thermo-fluid dynamic analysis. In this study, a computational fluid dynamic (CFD) methodology has been developed for the complete assessment of the energy performance of a prefabricated timber–concrete composite ventilated façade module in different operating conditions. Global numerical results are presented as well as local ones in terms of heat flux, air velocity, and temperature inside the façade cavity. The results show the dependency of envelope efficiency on solar radiation, the benefits that natural convection brings on potential energy savings and the importance of designing an optimized façade geometry. The results concerning the façade behavior have been thoroughly compared with International Standards, showing the good accuracy of the model with respect to these well-known procedures. This comparison allowed also to highlight the International Standards procedures limits in evaluating the ventilated façade behavior with the necessary level of detail, with the risk of leading to design faults.
Project contact is Pierre Blanchet at Université Laval
The work of Lessard et al. (2017) demonstrated that the building envelope was an important system in the building in terms of environmental impact, but only took into account the external components of the building envelope. This project will perform a life cycle analysis of the main building envelopes for a typical building under commercial construction. By relying on our design partners, the main systems and associated materials will be analyzed in a cradle-to-grave approach. It is desirable to identify hot spots and to indicate avenues for product development in order to reduce the envelope's environmental footprint. Among the scenarios to be considered: light framework, CLT, curtain walls and all their possible variants, but also commonly used non-biobased systems. The comparison between the systems studied will be based on an equivalent energy efficiency performance.
This report provides an overview of major changes occurred in the recent decade to design and construction of the building envelope of wood and wood-hybrid construction. It also covers some new or unique considerations required to improve building envelope performance, due to evolutions of structural systems, architectural design, energy efficiency requirements, or use of new materials. It primarily aims to help practicioners better understand wood-based building envelope systems to improve design and construction practices. The information provided should also be useful to the wood industry to better understand the demands for wood products in the market place. Gaps in research are identified and summarized at the end of this report.