CCBST 2017: 8 Presentations and 9 Papers

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Morrison Hershfield is proud to announce that we are having 9 papers featured and 8 presentations at this year’s Canadian Conference on Building Science and Technology (CCBST)!

Here’s a quick overview of our sessions taking place over the three-day conference:

Lessons Learned from Laboratory Testing Failures of Glazing Systems

Andy Lang, AScT – Building Science Specialist

Curtain walls and window walls are typically specified to meet a variety of different performance and testing criteria, some of which can be quite stringent.  Such requirements are defined in specific codes and industry standards, including, but not limited to new 2015 requirements of the National Building Code of Canada, the International Building Code, AAMA 501 – Methods of Test for Exterior Walls, and ASTM E2099 – Standard Practice for the Specification and Evaluation of Pre-Construction Laboratory Mockups of Exterior Wall Systems.

Critical Review of a Whole Building Air Leakage Testing Requirement

Lee Durston – Senior Building Science Consultant

Over the past decades, energy codes have brought a number of changes with respect to improving the performance of the building envelope both in design and construction.  With respect to the building enclosure, the most debatable is the increasing importance placed on air-leakage and how this often unknown value affects many of the energy efficiency metrics that define the performance of the building.  Throughout the world, there are multiple codes and standards requiring varying levels of air tightness as well as varying performance levels and methods of verification. As the requirements and performance implications become better understood, common design and construction practices will experience shifts toward improved performance, as was experienced in the early years of the USACE requirements on which the private sector codes are based.  However, variations between these standards and performance testing requirements have also brought about questions as to whether the testing is warranted and truly beneficial.  Through a review of multiple case studies of past and current enclosure consulting and whole building air leakage testing, including high-rise, multi-family, and other commercial new and renovation construction, this presentation will provide a critical review of these codes and standards for validity, impact, and relevance.

A Case History Review of ETFE on Today’s Current Projects

Lee Durston – Senior Building Science Consutlant

ETFE, the fluorocarbon-based polymer ethylene tetrafluoroethylene, is quickly gaining popularity in North America with it’s use on some of the continent’s most prominent projects.  ETFE was developed for architectural purposes in the 1970s, and since that time, mainstream use of ETFE in construction projects has been largely limited to Europe. The material has many attractive attributes that provide not only a new aesthetic quality, but also potential cost savings.  Weighing in at roughly one percent of the weight of glass, significant reductions in structural costs are made possible by employing ETFE. Despite these great potential benefits, the material is not an equal substitution to glass or other roofing systems in many respects.  Through review of material characteristics, performance modeling, and multiple case studies of current ETFE installations, the authors will discuss lessons learned, limitations, as well as the benefits of the material from the perspective of building science implications.

A Compartmentalization & Ventilation System Retrofit Strategy for High-rise Residential Buildings in Cold Climates

Matt Carlsson – Building Science Consultant, et al

This research proposes an alternative rehabilitation strategy for aging high-rise multi-unit residential buildings (MURBs) involving suite compartmentalization and decentralizing the ventilation system. Energy efficiency retrofits of MURBs today tend to focus on increasing the thermal performance and air-tightness of the enclosure, which neglects the inherent inefficiency and ineffectiveness of pressurized corridor ventilation systems, and often amplifies deficiencies. An alternative approach is to isolate the suites from the corridors, and install balanced heat recovery ventilators in each. Ventilation can then be maintained at design rates, and regulated according to need. This proposed retrofit was investigated for an existing high-rise MURB in Vancouver. Computer simulation using EnergyPlus™ (v.8.4.0) was used to examine the impact of the proposed retrofit on the case study building. Results show annual heating energy decreased by 51% and overall GHG emissions decreased by 29%. The main benefit of the proposed retrofit, however, is improved zone air distribution of the mechanical ventilation system. Because building enclosure air-tightness improvements can negatively impact air distribution in buildings with pressurized corridor ventilation systems, the proposed retrofit should be applied in combination with, or before, an enclosure retrofit. Thermal resilience should also improve, with longer passive surviveability durations from a reduction in uncontrolled air leakage induced by stack effect.

Insulated Metal Panels – Design and Construction Challenges:

Harold Louwerse, BTech, RRO – Building Science Consultant

Exterior insulated assemblies are growing in popularity due to changing code requirements with regards to thermal resistance for opaque wall assemblies. Simply installing batt insulation inside the stud cavity is not sufficient any more. Moving forward, the now obvious thermal benefits of continuous insulation combined with improvements in technology and manufacturing over the last 10-15 years have propelled exterior insulation assemblies to the forefront of envelope solutions.  Insulated Metal Panels (IMP’s) are one of the exterior insulation options that Owners, Architects and Engineers now consider an attractive, cost effective, all-in-one building envelope solution.  IMP’s are being used on a growing number of projects as the air, vapour, moisture barrier, cladding and insulation, or a combination thereof.  Designing and constructing wall assemblies with IMP’s can be a simple and effective method of enclosing a building, but it may pose challenges, especially on complex geometric buildings.  Challenges could include integrating the IMP’s with other building envelope assemblies or achieving the desired airtight and thermally efficient building envelope from an installation perspective.

Design Limits for Framed Wall Assemblies Dependent on Material Choices for Sheathing Membranes and Exterior Insulation

Ivan Lee – Building Science Consultant, Mark Lawton – Senior Building Science Specialist & Patrick Roppel – Building Science Specialist

There are many opinions in industry with regard to appropriate material choices for sheathing membranes and exterior insulation of framed wall assemblies.  Opinions vary on what is sensible for the vapour permeance of materials outboard of the framing so that not only will wetting and drying will be in harmony, but other interests such as costs, wall thickness, and energy efficiency targets can be met.

Fenestration Systems – It Is All About the Plumbing!

Peter Adams, P.Eng. – Senior Building Science Specialist & Yvon Chiasson, P.Eng. – Building Science Specialist

A few years ago the Toronto office of our engineering firm experienced what we termed “the year of the crappy curtain wall”. In actuality it was more like eighteen months, and during that period we investigated persistent water penetration in several low- to mid-rise commercial office buildings ranging in age from 5 to 20 years old. The failures discovered were not unique to curtain wall systems and were entirely avoidable if those responsible had even a basic understanding of how these systems are supposed to function. For several of the buildings we investigated, the failures were in conventional, fully captured curtain wall systems that were not installed correctly from the get go. There are many excellent, qualified curtain wall installers out there, but apparently they were off benefiting other jobs when these buildings were constructed.

Quantifying the Benefit of Venting Glazed Spandrels to Reduce Glass Breakage and Control Moisture

Julien Schwartz – Building Science Consultant & Patrick Roppel – Building Science Specialist
Stephane Hoffman – VP / Senior Building Science Specialist & Neil Norris – Building Science Engineer

While venting glazed spandrels is cited to be a benefit to control heat buildup, several instances of spontaneous glass breakage in spandrel insulated glazing units, attributed to thermal stress, have been reported in vented spandrel cavities used with an opacifier on the inside glass surface. The implication is that if venting is not an effective solution to reduce thermal stress and the associated need for higher strength glass, then it is desirable not to vent to avoid dirt buildup on the inside glass surface as it cannot be cleaned. The benefit of venting or weep holes must also be evaluated in terms of condensation risk and damage.