Supporting Reference

Windows, Overview of Issues for the ExAC

Windows, overview of issues is a 15-page conference paper by M. Z. Rousseau, published by the National Research Council of Canada (NRC) in 1988. It defines the window performance framework that still shapes how architects specify and detail fenestration, and it appears on Examitect's ExAC study plan as a supplementary reference for building science, assemblies, and environmental separation.

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Windows, overview of issues overview

Windows at a glance

Full titleWindows: overview of issues
AuthorM. Z. Rousseau, NRC Institute for Research in Construction
PublisherNational Research Council of Canada (NRC). Published in the proceedings of Building Science Insight '88: Window Performance and New Technology.
YearAugust 1988
Length15 pages (pp. 1-15)
NRC numberNRCC 29348(1). DOI: 10.4224/40001236.
LanguagesEnglish. French versions of many Building Science Insight papers are available through the NRC Publications Archive; check the archive record to confirm.
Primary audienceArchitects, building scientists, and envelope practitioners working with window selection, specification, and detailing in Canadian climates.
ExAC relevanceSupplementary reference on Examitect's ExAC study plan for Section 2 (5.21, environmental separation) and Section 3 (8.2, building science and systems).
Where to accessFree PDF through the NRC Publications Archive at nrc-publications.canada.ca. Search for NRCC 29348(1) or use DOI 10.4224/40001236.

Why Windows matters for the ExAC

Windows are the most performance-critical component in a Canadian building envelope. A wall can be detailed around many failures; a poorly specified or installed window drags thermal, air, moisture, acoustic, and fire performance down together. The Examination for Architects in Canada (ExAC) tests whether you understand those interactions.

The paper is listed as a supplementary reference on Examitect's ExAC study plan for Section 2 environmental separation (NBC Part 5, category 5.21) and Section 3 building science and systems (category 8.2). Primary references for those objectives are NBC 2020, CHING, and CHOP, but the vocabulary in Rousseau's paper is what makes those primary references readable when they address fenestration. Terms like air leakage class, rain penetration resistance, vapour flow, sound transmission class, and fire-rated glazing all appear in NBC 2020 and CHING, and this is where they are defined in plain language for practitioners.

You do not need this paper to answer every window question on the ExAC. You do need the performance framework it describes. One focused read early in your study schedule will pay back many times over when those terms appear in scenario questions.

How to study Windows for the ExAC

  • Read it in one sitting. The paper is 15 pages. Block forty-five minutes early in your study schedule and read it straight through. You are building a performance vocabulary, not memorizing facts.
  • Map the seven performance categories to NBC 2020. After reading, write moisture, air, vapour, rain, and thermal beside the corresponding Part 5 control functions, then map sound to NBC 9.11 and fire spread at glazing to the spatial separation provisions. That mapping is the core testable skill.
  • Prioritize moisture, air, and rain penetration. These three categories appear most often in ExAC scenario questions and are the failure modes NBC Part 5 addresses most directly.
  • Learn the vocabulary, not the products. The 1988 product survey is dated. What carries forward is the vocabulary: air leakage class, vapour flow resistance, rain penetration resistance, STC, fire-rated glazing, and U-value.
  • Connect glazing thermal performance to the NECB. The paper addresses window thermal resistance in the context of the full unit. Connect this to fenestration U-value requirements in NECB 2020 and to the thermal bridging covered in the Building Envelope Thermal Bridging Guide.
  • Pair the paper with CHING's chapters on doors and windows and on moisture and thermal protection. CHING provides the visual assembly context the paper's text describes. Reading them together builds the mental model you need for assembly and scenario questions alike.

ExAC sections Windows supports

  1. Section 2: Codes

    Supplementary for environmental separation objectives under NBC 2020 Part 5. The paper's seven-category framework maps directly to the heat, air, vapour, and water control functions that Part 5 regulates at glazed openings, with sound covered by NBC 9.11 and fire spread at glazing by the spatial separation provisions.

  2. Section 3: Sustainability and Final Project

    Supplementary for building science, systems, and assemblies objectives. The paper's system-level view of window components and its envelope performance framework support both conceptual and detail-level questions in this section.

Inside the paper: the four topic areas

Rousseau organizes the paper around four main topics. The second is the most exam-relevant; the others provide context and vocabulary you will draw on when reading NBC Part 5 and CHING.

Topic areaWhat it coversWhere it lands on the ExAC
Windows as a system of elements Frame materials, glazing types, spacers, sealants, weatherstripping, and hardware, treated as a single performance unit. Introduces the idea that a window fails as a system, not as a single part. Section 3 assemblies and detailing. Relevant when a question asks which component is responsible for a particular performance failure.
Windows as part of the building envelope The seven performance categories: moisture performance, air leakage, vapour flow, rain penetration, sound propagation, fire spread through glazings, and thermal performance. Frames each category in terms of failure consequences and the design parameters that control them. Section 2 environmental separation and Section 3 building science. Five of the seven categories map directly to NBC 2020 Part 5 control functions; sound falls under NBC 9.11 and fire under the spatial separation provisions. The most exam-relevant section of the paper.
Windows as part of the indoor environment Interior condensation on glass and frames, daylight and glare, view to the exterior, and acoustic comfort inside the building. Treats windows as the interface between the interior programme and the exterior climate. Section 1 schematic design and design development, and Section 3 building science. Interior condensation in particular is testable alongside NBC Part 5 requirements.
Window market offerings and components A 1988 survey of available window types, frame materials, glazing options, and component combinations. Dated in product specifics but useful as a classification framework for understanding assembly categories. Background only. The classification approach has value; the specific product details are not examined on the ExAC.

If you are short on time, focus on the second topic area and treat the others as useful context. The seven performance categories from that section are the paper's lasting contribution to ExAC preparation.

Key window terms every ExAC candidate should know

These terms come from the paper's performance framework and from the related NBC 2020 and CHING content. Knowing them before the exam lets you parse scenario questions faster.

TermWhat it means for the ExAC
FenestrationWindows, skylights, glazed doors, and other glazed openings in a building envelope. Subject to thermal, moisture, air, and vapour requirements under NBC 2020 Part 5, with sound addressed under NBC 9.11 and fire at glazed openings under the spatial separation provisions.
GlazingThe glass or transparent infill panel in a window unit. Single, double, and triple glazing differ in U-value, solar heat gain coefficient, and condensation risk on interior surfaces.
Air leakage (windows)Uncontrolled air flow through and around the window unit, including frame joints, sash weatherstripping, and the perimeter seal at the rough opening. Carries energy and moisture in both directions.
Rain penetration resistanceThe ability of the window unit and its perimeter installation to prevent water from entering the building. Most rain penetration failures occur at the perimeter installation detail, not in the glazing unit itself.
Vapour flowDiffusion of water vapour through window frames, spacers, and glazing edge seals. Poor vapour control leads to fogging inside a sealed glazing unit (seal failure) or condensation on the interior frame surface.
Sound transmission class (STC)A single-number rating of a window assembly's ability to reduce airborne sound. Higher STC values indicate better sound isolation. Relevant for mixed-use buildings and units near noise sources.
Fire-rated glazingGlazing assemblies tested and listed to limit fire and smoke spread for a rated duration. Required by NBC 2020 where spatial separation limits unprotected openings or where fire compartments are maintained at glazed partitions.
Fenestration U-valueThe thermal transmittance of a window assembly in W/m2K, measured for the whole unit including frame and edge effects. The NECB 2020 sets maximum U-values for fenestration by climate zone. Lower U-value means better thermal resistance.
Environmental separation (fenestration)The window assembly's function under NBC 2020 Part 5 to separate conditioned interior space from exterior conditions, controlling heat, air, vapour, water, and structural loads at the glazed opening.
Window systemThe complete assembly of frame, sash, glazing, spacer, sealants, weatherstripping, hardware, and perimeter installation, treated as a single performance unit.
Condensation resistanceThe ability of a window frame and glazing edge to keep interior surface temperatures above the dew point, preventing visible condensation that signals heat loss and potential mould risk.
Perimeter installation detailThe junction between the window frame and the surrounding wall assembly, including the air seal, flashing, sill pan, and drainage plane. Most window performance failures happen here, not in the glazing unit.

Tips for Intern Architects reading Windows, overview of issues

The paper was written for building science practitioners at a 1988 conference, not for exam candidates today. Here is how to read it efficiently for the ExAC.

Tip 1, read it as a vocabulary primer, not a textbook. The paper's lasting value is its performance framework: seven categories, three frames of reference, and the idea that a window is a system. Read it once with that framing in mind and you will retain what matters for the exam.

Tip 2, prioritize the envelope section. The topic area covering windows as part of the building envelope is the most exam-relevant. It maps directly to NBC 2020 Part 5 environmental separation categories. Spend most of your reading time there and treat the indoor environment section as useful context.

Tip 3, the perimeter installation is where failures happen. Rousseau's framework makes clear that most window performance failures, whether air, water, vapour, or acoustic, occur at the perimeter installation detail rather than in the glazing unit itself. When a scenario question describes a window problem, look at the perimeter first.

Tip 4, windows bridge multiple control layers simultaneously. NBC 2020 Part 5 requires control of heat, air, vapour, and water at the envelope, NBC 9.11 adds sound control, and the spatial separation provisions govern fire spread at glazed openings. A window is the only component that must address all six at once. The paper's multi-category framework is built around this fact. Internalize it and multi-variable scenario questions become easier to parse.

Tip 5, skip the 1988 product details. The market survey section describes specific frame materials, glazing types, and hardware from more than thirty-five years ago. Skim it to understand the classification approach, then move on. Specific products are not examined and many no longer reflect current practice.

Tip 6, connect condensation to both thermal and moisture control. The paper treats interior window condensation as an indoor environment issue, but it is simultaneously a thermal bridging issue (the frame runs cold) and a vapour issue (humid interior air meets a cold surface). NBC Part 5 reads it the same way. When you see a condensation question, expect the answer to require both a thermal and a moisture control lens.

Tip 7, do not over-invest. The paper is a supplementary reference on Examitect's ExAC study plan. One focused read is the right investment. Spend the bulk of your fenestration study time on NBC Part 5, CHING, and CHOP, and use the Rousseau paper as the vocabulary bridge that makes those primary references click into place.

Common ExAC scenarios where Windows, overview of issues is the answer

These question types appear in Section 2 environmental separation categories and Section 3 building science and assemblies categories. The performance framework from Rousseau's paper is what you need to parse them quickly.

  • A residential project in a cold climate specifies aluminum-frame windows without a thermal break. The energy consultant flags a concern. Which performance categories from the window system framework are at risk, and what change to the specification addresses the problem?
  • Rain is infiltrating through a newly installed window on a mid-rise building, but the window unit passed the factory test. Site review reveals no sill pan flashing at the rough opening. Which part of the window system has failed, and what does the performance framework say about where rain penetration failures typically occur?
  • A mixed-use building has residential suites above a retail music venue. The architect must specify windows for the suites that limit sound transmission from below. Which performance category applies, and what window characteristic should the specification address?
  • A curtain wall elevation on a commercial project includes a section adjacent to a required fire separation. The design uses standard clear float glazing throughout. Which performance category flags a compliance issue under NBC 2020, and what does the window system framework recommend?
  • An energy modeller reports that the building passes the NECB 2020 compliance path when using centre-of-glass U-values but fails when whole-unit U-values are used. What does the window system framework say about the difference, and what design moves can close the gap?
  • A post-occupancy review finds visible condensation on the interior surface of window frames in a high-humidity occupancy such as an indoor pool facility. The glazing unit itself is not fogged. Which performance categories are at play, and what would a corrective specification address?
  • A heritage restoration project must replace single-glazed windows with assemblies that match the original profiles while improving thermal and moisture performance. Which performance categories must be balanced, and what does the paper's system frame say about the tradeoffs between frame, glazing, and perimeter detailing choices?

Each scenario tests whether you can assign the right performance category and then identify the design move that addresses it. The paper's framework is the tool that makes that assignment fast and accurate under exam pressure.

How Windows compares to other ExAC references

The paper sits in a cluster of envelope and fenestration references on Examitect's ExAC study plan. Use this table to decide which reference to open for which kind of question.

ReferenceWhat it is forHow Windows relates
Windows, overview of issuesPerformance vocabulary and framework for window systems in Canadian climates.The vocabulary primer that makes the other references readable when they discuss fenestration.
NBC 2020, Part 5Mandatory requirements for environmental separation: heat, air, vapour, and water at the building envelope. Sound control sits in NBC 9.11 and fire at glazed openings under the spatial separation provisions.NBC Part 5 is the regulatory framework. The paper defines the performance categories that Part 5 regulates.
CHING (Building Construction Illustrated)Building science and assemblies with detailed illustrations. Chapters on doors and windows and on moisture and thermal protection cover fenestration assembly and detailing.CHING is the primary reference for fenestration assembly; the paper is the vocabulary context behind it.
CHOP, Chapters 2.5 and 5.5Standards organizations, certification and testing agencies, and sustainable, regenerative, and resilient design.CHOP frames the standards and sustainability context behind fenestration selection and specification. The paper explains the performance criteria that inform those decisions.
NECB 2020Energy performance requirements for buildings, including maximum fenestration U-values by climate zone.The NECB sets the U-value targets. The paper explains why fenestration U-values matter in the context of the full window system.
Building Envelope Thermal Bridging GuideMethodology and catalogue for thermal bridging in opaque envelope assemblies and interface details.The Thermal Bridging Guide covers opaque assemblies; this paper covers glazed ones. Together they address the full envelope thermal performance picture.
Rainscreen Exterior Wall DesignRainscreen wall design and the pressure-equalized drainage plane that protects against rain penetration.The rainscreen principle applies to the wall cavity; the paper's rain penetration section covers the window unit and its perimeter installation. Read them as complements.

How Examitect reinforces Windows, overview of issues

Reading the Rousseau paper once gives you the performance vocabulary. Examitect's question bank puts that vocabulary to work in the scenario format the ExAC uses. Section 2 environmental separation questions and Section 3 building science and assemblies questions both draw on the fenestration performance framework, and each answer explanation points back to the specific category the question is testing. You learn which category, not just which answer.

You also get full-length mock exams that match ExAC pacing and free study notes for every section. Try a few sample questions to calibrate where you stand, then review pricing when you want the full bank.

FAQ

Windows, overview of issues FAQ

Windows, overview of issues is a 15-page conference paper by M. Z. Rousseau, published by the National Research Council of Canada's Institute for Research in Construction in August 1988 as part of the Building Science Insight '88 proceedings. It examines window performance from three angles: windows as a system of components, windows as part of the building envelope, and windows as part of the indoor environment. It also surveys the range of window types and components available at the time of writing.

The paper was written by M. Z. Rousseau and published in August 1988 by the NRC Institute for Research in Construction. It appeared in the proceedings of Building Science Insight '88, a conference focused on window performance and new technology. The NRC number is NRCC 29348(1) and the DOI is 10.4224/40001236. It is freely available through the NRC Publications Archive.

The paper is listed on Examitect's ExAC study plan as a supplementary reference for Section 2, category 5.21 (understand environmental separation requirements, NBC Part 5) and Section 3, category 8.2 (building science and systems). Primary references for those objectives are NBC 2020, CHING, and CHOP.

Yes, for vocabulary and principles. The paper defines the performance categories that still frame how architects specify windows: moisture performance, air leakage, vapour flow, rain penetration, sound propagation, fire spread through glazings, and thermal resistance. These categories appear in NBC 2020 and CHING today. Specific product details from 1988 have evolved, but the performance framework the paper establishes is the same framework the ExAC tests.

Seven categories: moisture performance (including condensation), air leakage and air tightness, vapour flow and vapour diffusion, rain penetration and drainage, sound propagation and sound transmission, fire spread through glazings, and thermal performance. The paper frames each from both an envelope standpoint and an indoor environment standpoint, which matches how NBC 2020 Part 5 organizes environmental separation requirements.

No. The product survey reflects 1988 market offerings and is dated. What you need is the performance vocabulary: air leakage class, vapour flow resistance, rain penetration resistance, sound transmission class (STC), fire-rated glazing, and fenestration U-value. Those terms appear in current ExAC questions regardless of which specific window products are on the market today.

Read it once as a fenestration vocabulary primer. It is 15 pages and a fast read. Then use CHING for the visual assembly context, NBC 2020 Part 5 for the regulatory requirements, and the Building Envelope Thermal Bridging Guide for thermal performance numbers at the window-to-wall interface. CHOP Chapters 2.5 and 5.5 cover standards organizations, certification and testing agencies, and sustainable design, which is where window standards and performance targets show up in practice.

The paper is freely available through the NRC Publications Archive at nrc-publications.canada.ca. Search for NRCC 29348(1) or the author name Rousseau, or use the DOI 10.4224/40001236 to go directly to the record. Check the archive record for a French-language version if you are studying in French.

Keep exploring

Other ExAC reference books.

Windows, overview of issues is one of several envelope and building science references on Examitect's ExAC study plan. Continue with the rest.

NBC 2020

National Building Code of Canada. Part 5 (environmental separation) is the primary code reference for the performance categories the paper defines.

CHING

Building Construction Illustrated. Primary reference for fenestration assembly and detailing in Section 3, with illustrations that pair directly with the paper's vocabulary.

CHOP

Canadian Handbook of Practice. Chapters 2.5 and 5.5 cover standards organizations, certification and testing agencies, and sustainable design, the practice context behind fenestration specification.

Building Envelope Thermal Bridging Guide

Covers thermal bridging in opaque assemblies and interface details, including the window-to-wall junction where much of the fenestration heat loss occurs.

Rainscreen Exterior Wall Design

The rainscreen principle governs the wall cavity where the window perimeter installation must integrate. Read alongside the paper's rain penetration section.

NECB

National Energy Code of Canada for Buildings. Supports the envelope and energy questions in Section 2.

RSMeans

RSMeans Cost Data. North American construction cost data, used for Section 1 Cost Management questions.

Yardsticks

Hanscomb Yardsticks for Costing. Canadian elemental cost data by building type and region, for Section 1 Cost Management.

Supporting references

The extended reading list of supplementary references that appear across Examitect's ExAC study plan.