Wahid Maref

École de Technologie Supérieure · Département de génie de la construction

Field monitorings of thermal performance of residential 2 x 6 wood-frame wall systems that had been retrofitted using vacuum insulation panels (VIPs) and extruded polystyrene foam (XPS) panels were undertaken in May 2011 - May 2012 at the Field Exposure of Walls Facility (FEWF) of NRC-Construction. The main objective of this research was to measure...

The building envelope provides thermal comfort, an excellent visual view, and sunlight for the occupants. It consists of two parts: (i) an opaque (non-transparent) part (e.g., walls and roofs) and (ii) a transparent part (e.g., windows, curtain walls, and skylight devices). Recently, the use of fully-glazed facades, especially in large cities, has...

This document is a case study of hemp-based materials integrated into the building envelope for African and North American’s applications. The objective is to evaluate the energy performance of hemp concrete for construction in Montreal, Canada, where heating predominates and in Dori, Burkina Faso, where air conditioning predominates. The effect of...

The overall building performance depends mainly on the energy performance, indoor air quality, and moisture performance. In order to accurately calculate the building performance, the development of a model with the ability to integrate all three performances is required. In this research, a combination of three models namely EnergyPlus for energy,...

This article performed a comprehensive review of the different state-of-the-art of roofing technologies and roofing materials and their impact on the urban heat island (UHI) and energy consumption of buildings. The building roofs are the main sources of undesirable heat for buildings, especially in warm climates. This paper discusses the use and ap...

In this paper, an integrated model that coupled CONTAM and WUFI was developed to assess the indoor air quality (IAQ), moisture, and thermal comfort performance. The coupling method of CONTAM and WUFI is described based on the exchange of airflow rate control variables as infiltration, natural and mechanical ventilation parameters between heat and m...

Many previous studies by the authors of this paper and others have shown that installing white/reflective/cool roofing systems resulted in energy savings. The amount of energy savings depended on the longwave thermal emissivity and the short-wave solar reflectivity of the rooftop surfaces. The question is “what is the percentage energy savings for...

Thermal potential for cooling and heating can be achieved by new configuration of earth–air heat exchanger (EAHE). This paper presents a numerical investigation of thermal performance of a spiral-shaped configuration of EAHE intended for the summer cooling in hot and arid regions of Algeria. A commercial finite volume software (ANSYS FLUENT) has be...

In building applications, there is a dynamic interaction/coupling between the energy performance and the indoor air quality (IAQ) performance. Previously, the performance of energy consumption (EC) and IAQ has been evaluated independently. In this study, an energy performance model (EnergyPlus) and IAQ performance model (CONTAM: contaminant transpo...

A field research study was conducted to investigate the wetting and drying characteristics in three 2 × 6 wood-framing wall specimens when they were subjected to different heat, air, and vapor flow transmission. The stud cavity of the wall specimens were filled with glass-fiber insulation having a nominal thermal resistance of R-20. The three wall...

Cool/white roofing systems use paints and membranes with high solar reflectivity to reflect a portion of the incident solar radiation resulting in lowering the temperature of the exterior surfaces in respect of the conventional/black roofing systems. This study focuses on the energy performance of roofing system that is being used in buildings of t...

The building performances are related to Energy Efficiency and Indoor Air Quality (IAQ). Modeling is one of the best accurate tools for measuring the building performance. Nowadays, Energy Efficiency and IAQ are modeled individually for buildings. Improvement strategies in both areas are analyzed separately. The fundamental problem in Energy and IA...

Many parts of the building envelopes contain enclosed airspaces. Also, the insulating glass units in fenestration systems, such as curtain walls, windows, and skylight devices, contain enclosed spaces that are normally filled with air or heavy gas such as argon, xenon, or krypton. The thermal resistance (R-value) of an enclosed space depends mainly...

Thermoelectric devices are currently being used in the applications of cooling and generating electricity. This study mainly focuses on using these devices for both applications toward cooling down computer chips. An important aspect in designing the cooling system is to minimize the non-uniformity of the temperature distribution in the computer ch...

In regions with hot climatic conditions such as that in Saudi Arabia, a substantial share of energy is used for cooling the buildings. Many studies have shown that cool (white) roofs can help reduce the cooling energy load and thus the demand for energy over time. Also, cool roofs help reduce the urban heat island during the summer time. This resea...

This case study evaluates the best energy efficiency measures of an existing two-story office building from the late 1960s located in Vancouver. Natural gas was used for heating and electricity was used for lighting, cooling and other needs. The building was simulated to match both metered data and bills. The energy model allowed identifying the pa...

Over the years, the energy efficiency of the North American housing stock has significantly improved mainly due to higher insulation levels, more efficient windows and, more importantly, adoption of various energy efficiency measures by building codes. The increased insulation levels of building envelopes for homes leads to a multitude of opportuni...

The National Research Council of Canada has undertaken field monitoring and computer modelling to investigate the risk of condensation in wall assemblies having different combinations of increased thermal resistance (R-value) of cavity insulation and of selected exterior insulation products. A set of three wall assemblies with different types of ex...

This report focuses on the Thermal Performance Testing of a Curtain Wall Panel. The full-scale testing of a thermally broken, double-glazed, commercially available, curtain wall system was carried out at test laboratories of CLEB Building Sciences. A curtain wall system was supplied by a Canadian manufacturer. Accordingly, in this report a descript...

SÉMINAIRE CEBQ #216: “LES RISQUES DE CONDENSATION ET DE MOISISSURE DANS LES ASSEMBLAGES MURAUX ”

SÉMINAIRE CEBQ #216: “LES RISQUES DE CONDENSATION ET DE MOISISSURE DANS LES ASSEMBLAGES MURAUX ”

Results from hygrothermal simulation are summarised in which the response of a series of 11 wood-frame wall assemblies are compared to a Reference wood-frame wall when subjected to the climate conditions of Tofino, BC, Vancouver BC, and St. John’s NL. Results from simulation of wood-frame walls and the Reference wall are provided over a two year si...

The National Research Council of Canada (NRC) has undertaken a research project to investigate the risk of condensation and mould growth in 2x6 wood-frame wall assemblies associated with increasing the thermal resistance (R-value) of cavity insulation for various scenarios of exterior insulation products. The project was requested by the Task Group...

The National Research Council of Canada (NRC) has undertaken a research project to investigate the risk of condensation and mould growth in 2x6 wood-frame wall assemblies associated with increasing the thermal resistance (R-value) of cavity insulation for various scenarios of exterior insulation products. The project was requested by the Task Group...

Constructing mid-rise wood-frame buildings will extend the exposure of the structural wood components to moisture and its effects during the construction phase, unless additional measures are implemented to prevent this from occurring. This means that the wood-based components of the walls will be more exposed to wind-driven rain. Designers should...

Reflective insulations are being used in attics, flat roof, and wall systems. Numerical modeling and experimental investigations were conducted to assess the thermal performance of assemblies with reflective insulations. In this article, the present model was used to verify the use of the ASTM C-518 test method for measuring the effective thermal r...

Windows generally have the lowest temperature index in current building types, and will consequently be the primary location for interior surface condensation. Surface temperatures can easily be calculated using thermal finite-element models, but these generally omit the effect of convection in the windows and the window–wall interface. Hence, ther...

In basement wall systems, airspaces can contribute in obtaining a higher thermal resistance, if a low-emissivity material such as reflective foil is installed within a furred-airspace. In this study, numerical simulations were conducted using the hygrothermal model ‘hygIRC-C’ that was developed at the National Research Council of Canada’s Institute...

A wall energy rating (WER) system has been proposed to account for simultaneous thermal conduction and air leakage heat losses through a full-scale insulated wall system. Determining WER requires performing two standard tests on a full-scale wall specimen: a thermal resistance test and an air leakage test. A 3D model representation of the wall spec...

This publication compiles the heat, air and moisture transfer terminology existing in books, standards and other reference documents. A small introduction is provided in Chapter 1 to present the CIB Commission W040 – Heat and Moisture Transfer in Buildings and to summarise the Commission activities since its formation in 1969. Chapter 2 indicate...

ABSTRACT Field monitoring of the dynamic heat transmission characteristics through Insulating Concrete Form (ICF) wall assemblies was undertaken in 2009-10 at National Research Council Canada’s Institute for Research in Construction’s (NRC-IRC) Field Exposure of Walls Facility (FEWF). The scope of work included the design of the experiments, the i...

Despite recent advances in highly performing envelopes that are technically feasible and can reduce heat loss by about one half, most current construction still just meets the provincial building code minimum of 2” x 6” constructions with conventional batt insulation. This project addresses several barriers to the adaptation of new envelope systems...

The reduced thermal resistance due to thermal bridging through steel and concrete framing can have a significant impact on the whole building energy performance. Uncertainty about the thermal performance of the building envelope can lead to inefficient design of HVAC systems, building operation inefficiencies, inadequate condensation resistance at...

A 3D numerical model was developed to investigate the effect of foil emissivity on the effective thermal resistance of an above-grade wall assembly with foil bonded to wood fibreboard in a furred assembly having airspace next to the foil. This model solved simultaneously the energy equation in the various material layers, the surface-to-surface rad...

The paper reports on a laboratory evaluation of conditions suitable for the formation of condensation at the window frame perimeter of the interface assembly as a function of both temperature deferential and air leakage rate across the test assembly. A summary of the laboratory test protocol is provided that includes a description of the test set-u...

Field monitoring of the dynamic heat transmission characteristics through Insulating Concrete Form (ICF) wall assemblies was undertaken in 2009-2010 at National Research Council Canada?s Institute for Research in Construction?s (NRC-IRC) Field Exposure of Walls Facility (FEWF). The main objective of this research is to evaluate the dynamic heat tra...

Maintenance of building façades and related systems should be an on-going process. Nonetheless, maintenance prioritisation issues are often neglected due to the lack of available tools to assess vulnerability to climatic effects and susceptibility to deterioration. How is climatic information currently accessed and used and what are the existing me...

The development of alternative details to manage water intrusion at the wall-window interface has produced a number of novel approaches to detailing the interface between the window and adjacent wall assembly. Many of these approaches advocate the need to provide drainage at the rough opening of the window subsill given that the window components t...

Field monitoring of the dynamic heat transmission characteristics through Insulating Concrete Form (ICF) wall assemblies was undertaken in 2009-2010 at National Research Council Canada’s Institute for Research in Construction’s (NRC-IRC) Field Exposure of Walls Facility (FEWF). The main objective of this research is to evaluate the dynamic heat tra...

Using Polyurethane Spray Foams (SPFs) as insulation in buildings provide durable and efficient thermal barriers. The industry is encouraging the SPF as an effective air barrier system in addition to its thermal insulation characteristics. In an effort to address these issues, a consortium of SPF manufacturers and contractors, jointly with the Natio...

As part of a research program to establish the hygrothermal response of wood-frame wall assemblies to varying climate conditions, a series of drying experiments were performed in a programmable environmental chamber used to replicate exterior climatic conditions. In these experiments, bulk moisture content of the assembly was measured using a weigh...

Recent research in the assessment of hygrothermal response of building enclosures focuses on both laboratory experimentation and modeling in which the results from both processes are compared. Evidently such type of studies can potentially offer useful information regarding the benchmarking of models and related methods to assess hygrothermal perfo...

This paper reports on experimental results and the use of an advanced hygrothermal computer model called hygIRC to assess the hygrothermal response of various components in wood-frame wall assemblies when subjected to nominally steady-state environmental conditions. There was interest in obtaining information on the drying rates of wall components,...

A Wall Energy Rating (WER) system has been proposed to account for simultaneous thermal conduction and air leakage heat losses through a full-scale wall system. Determining the overall WER requires that two standard tests be performed on a full-scale wall specimen: a thermal resistance test and an air leakage test. A three-dimensional model represe...

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A weighing system was devised to conduct drying experiments on wood based products that could be used to compare results with those derived from simulation. The experiments were designed to retrieve data on the change in weight of specimens continuously over time from which the hygrothermal response of the specimens could then be determined. Specim...

Effective moisture control in the building envelope is essential if acceptable service life is to be achieved for the built environment. Effective moisture control implies both minimizing moisture entry into the system, and maximizing the exit of moisture, which does enter, so that no component in the system stays 'too wet' for 'too long'. But what...

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This paper provides highlights of the research work carried out at the National Research Council Canada, Institute for Research in Construction on assessing the hygrothermal performance of wall systems that included this innovative vapour retarder (Note: Vapour Barrier in Canadian terminology is equivalent to Vapor retarder in US terminology). The...

Considerable efforts are recently focusing on energy labeling of components and systems in buildings. In Canada, the energy rating of windows was established, which provides a protocol to rate different types of windows with respect to their energy performance. It takes into account the interaction between: solar heat gain, heat loss due to air lea...

The application of polyurethane spray foam (SPF) insulation In buildings provides a durable and efficient thermal barrier. The industry is also promoting the SPF as an effective air barrier system in addition to Its thermal insulation characteristics. In an effort to address these issues, a consortium of SPF manufacturers and contractors, jointly w...

This paper describes a small study carried out using a hygrothermal simulation tool to investigate the sensitivity of wall performance results to uncertainty in the amount of rain impinging on the wall, Design standards for hygrothermal analysis of proposed designs include methods for selecting appropriate moisture reference years and specify the a...

The hygrothermal performance of building envelope systems is dictated by their responses to combined heat, air and moisture fluctuations produced by exterior and interior conditions. Research has focused on both laboratory experimentation and modeling of envelope systems by computer programs (hygrothermal tools). Experimental studies played a cruci...

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For the computer modelling, researchers in NRC-IRC?s Building Envelope and Structure program provided the expertise, using their hygrothermal modelling tool, hygIRC 2-D. This tool creates a computational model of a building and subjects it to hourly temperature, relative humidity, solar radiation, and wind and rain variations on the outside, and te...