Wahid Maref

École de Technologie Supérieure, Construction Engineering, Faculty Member

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Dr. Wahid Maref is a Professor at École de technologie supérieure (ÉTS - Montreal), University of Quebec, in Construction Engineering Department. Prior to this position, Wahid was a Senior Research Officer at the NRC-Construction for more than 20 years. Prof. Maref has been involved in building science research for more than 25 years. His expertise is in moisture management in building envelopes. He has solved many hygrothermal designs and has developed multiple design guidelines for various envelope systems. His expertise is, as well, in Risk Management Assessment of Innovative Envelope Systems, which includes hygrothermal modeling, laboratory and field-testing. He is an active ASHRAE Member since 2003. He has been recognized by ASHARE in 2017 at Long Beach, CA, for his contribution to ASHRAE through the years and was honored with the Distinguished Service Award. He is a member of several Task Groups and Technical Committees of national and international standards and professional organizations and provides support on technical issues to the North American construction and related industries.

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Muhammad Hafeez Osman

Universiti Teknologi Mara

Gabriele Morra

University of Louisiana at Lafayette

Iosif Botetzagias

University of the Aegean

Peter D Clift

University College London

Anil M Pophare

RTM Nagpur University

Suman Paul

Presidency University, Bengaluru

Sergey Konovalov

Russian Academy of Sciences 1

Henry Nasution

Swiss Germany University

Carlo Doglioni

Università degli Studi "La Sapienza" di Roma

Christopher Scotese

University of Texas at Arlington

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Papers by Wahid Maref

Hygrothermal Performance of the Hemp Concrete Building Envelope

Energies, Apr 4, 2024

The search for environmentally friendly and low-carbon-footprint construction materials continues... more The search for environmentally friendly and low-carbon-footprint construction materials continues progressively. Researchers are now interested in innovative materials that connect with the principles of sustainable construction, and materials such as hemp concrete prove to be promising. This article presents the results of a study that aimed to evaluate the hygrothermal performance of hemp concrete integrated into the building envelope using the hygrothermal tool WUFI Pro 6.2. The simulation model was compared and verified with existing models before its utilization for this study. The results of this verification were in good agreement, which gave us more confidence in its application for further parametric studies of building envelopes in hot climate zones. Three wall systems were simulated: (i) a wall system with hemp concrete, (ii) a compressed earth block wall, and (iii) a cement block wall. The most important variables used in the simulations were the hygrothermal properties of the materials or wall components and the incident solar radiation. The simulation results showed that hemp concrete has good thermal performance and temperature and humidity regulation capabilities of the building envelope. The interior surface temperatures of the hemp concrete walls were between 22.1 • C and 24.6 • C compared to the compressed earth block and cement block walls, where the surface temperatures were between 22.0 • C and 27 • C and between 21.2 • C and 28.7 • C, respectively, and between 23 • C and 45 • C for the exterior temperatures. These values remain the same with the increase in exterior temperatures for hemp concrete walls. In conclusion, hemp concrete could be a great alternative material for use in construction for hot climate zones.

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Comparison of Thermal Insulation Proprieties between Glass Wool, Hemp Wool and an Experimental Material Composed of Pleurotus Ostreatus Mycelium and Ash Wood Chips

Energy performance of highly insulated wood-frame wall systems using a vip

Performing basement systems : Part I : Managing the water

Numerical parametric study of a new earth-air heat exchanger configuration designed for hot and arid climates

International Journal of Green Energy, 2019

Thermal potential for cooling and heating can be achieved by new configuration of earth-air heat ... more 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 spiralshaped configuration of EAHE intended for the summer cooling in hot and arid regions of Algeria. A commercial finite volume software (ANSYS FLUENT) has been used to carry out the transient threedimensional simulations and the obtained results have been validated using the experimental and numerical data obtained from the literature. The agreement between our simulation results and those from literature is very satisfactory. A parametric analysis of the new geometry of (EAHE) has been performed to investigate the effect of pitch, depth, pipe length and of the flow velocity on the outlet air temperature and the EAHE's mean efficiency as well as its coefficient of performance (COP). It has been shown that when the pitch space varies between 0.2 and 2 m the difference of outlet air temperature increases by 6°C. When the air velocity increases from 2 to 5 m/s the mean efficiency decreases from 60 % to 33 % and the COP of the EAHE decreases from 2.84 to 0.46.

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Risk of condensation and mold growth in wood-frame wall systems with different exterior insulations

The National Research Council of Canada (NRC) has undertaken a research project to investigate th... more 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 (TG) on Properties and Position of Materials in the Building Envelope, acting on behalf of the Standing Committee on Housing and Small Buildings (SCHSB). The work originated from a Code Change Request “CCR-802” in which it was suggested that the Water Vapour Permeance (WVP) limit be raised from 60 to 300 ng/(Pa•s•m2) while leaving the limit for air leakage of building envelope materials unchanged at 0.1 L/(s•m2) at a pressure difference of 75 Pa. In response to the CCR-802, NRC undertook a research study by conducting hygrothermal modelling using hygIRC-C model. The risk of condensation and mould growth in wall assemblies with wall cavity...

Field thermal mass performance of an insulating concrete form (ICF) wall

With the depletion of energy resources and the rising concerns about the environment, increasing ... more With the depletion of energy resources and the rising concerns about the environment, increasing the energy performance of buildings in Canada is a high priority. The objective of this paper is to present the preliminary results of research aimed at understanding and quantifying the impact of the concrete's thermal mass in insulating concrete form (ICF) wall assemblies. Field monitoring of the dynamic heat transmission characteristics of an ICF wall exposed to Ottawa's climate was carried out between October 2009 and April 2010, data were recorded every 15 minutes. Results showed that although it does not have a significant impact on the R-value of the wall in steady state conditions, the concrete is efficient in lowering the peak heat flux to the exterior during cold weather. This document provided useful information which can be used for energy simulation models, further experimental data will be available in later publications.

Thermal response of

basement wall systems with low-emissivity material and furred airspace

Performing basement systems : Part 2 : Managing heat and moisture

The effect of window-wall interface details on window condensation potential

Considering all building components, windows typically have the lowest surface temperature, and w... more Considering all building components, windows typically have the lowest surface temperature, and will consequently be the primary location for interior surface condensation. Those surface temperatures can easily be calculated using thermal finite-element-models (FEM), and there is an ISO standard with guidelines for condensation risk assessment. However, both the FEMsimulations as the ISO standard generally omit the effect of air flows in and around window frames. When cold air is drawn into the construction, the airflow might cool down specific components of the window-wall interface depending on the location of the airflow path. Consequently, the current evaluation method for condensation risk assessment based on FEMsimulations might underestimate the actual risk. There is a need to determine if interface details become more susceptible for surface condensation due to pressure differences over the component. This paper reports on a laboratory evaluation of condensation risk assessm...

La performance hygrothermique et énergétique de l'enveloppe des bâtiments : Partie II : Cote énergétique des murs isolés

Test facilities for evaluation of hygrothermal building envelope performances : NRC-IRC field exposure of walls facility, Canada

Field hygrothermal performance of retrofitted wood-frame wall assemblies in cold climate

Thermal analysis of curtain wall systems : a parametric study

HEADING The thermal performance of curtain wall systems can easily be calculated using 2D numeric... more HEADING The thermal performance of curtain wall systems can easily be calculated using 2D numerical simulations. Several commercial software packages are available, and international standards provide a methodology to calculate the thermal transmittance. However, even though these methods are well known in academia and the research community in general, thermal optimization has not reached its full potential in the building industry yet and there is considerable margin for improvement. Based on a market survey in North America and Europe, generic curtain wall sections were developed, and typical approaches for improving the thermal performance of curtain wall systems have been identified and described. Subsequently, the impact of separate improvements, as well as combined effects have been studied using both standardized and advanced calculation methods. For this, the heat transfer phenomena and the way these are modelled according to standard calculation procedures are discussed. M...

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Effective R-value of enclosed reflective space for different building applications

Journal of Building Physics, 2019

Many parts of the building envelopes contain enclosed airspaces. Also, the insulating glass units... more 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 on the type of the filling gas, emissivity of all surfaces that bound the space, the size and orientation of the space, the direction of heat flow through the space, and the respective temperatures of all surfaces that define the space. Assessing the energy performance of building envelopes and fenestration systems, subjected to different climatic conditions, requires accurate determination of the R-values of the enclosed spaces. In this study, a comprehensive review is conducted on the thermal performance of enclosed airspaces for different building applications. This review includes the computational and experimental methods for determi...

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Hygrothermal performance of wall and window systems

ABSTRACT

Benchmarking Hygrothermal Tools with Full-Scale Laboratory Drying Experiments

The hygrothermal performance of building envelope system is dictated by the response of the syste... more The hygrothermal performance of building envelope system is dictated by the response of the system to combined heat, air and moisture fluctuations produced by exterior and interior conditions that exist on either side of the envelope. This study was undertaken to generate information that would assist the benchmarking of a hygrothermal simulation model and related methods to assess hygrothermal performance of wall assemblies. This paper presents a series of drying experiments on oriented strand board (OSB) alone or in combination with different sheathing membranes designed to benchmark the hygrothermal simulation model called "hygIRC". It also presents preliminary results from a series of simulations in which the shape of the drying curve and the time taken to establish the equilibrium moisture content are determined and compared with the experimental results. This was one of several steps undertaken in a broader benchmarking exercise to validate the model and its implemen...

Methods for evaluating the moisture management of wood-frame wall systems

BC-BERC Proceeding, 2010

... ASHRAE/MEWS Property Database (RP 1018) Page 18. MEWS Proϕect: IRC Research Team Peter Beau... more

Evaluating window-wall interface details for risk of condensation on windows

The development of alternative details to manage water intrusion at the window-wall interface has... more The development of alternative details to manage water intrusion at the window-wall 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 themselves are susceptible to water entry over their expected life. Depending on the types of windows used and the cladding into which the windows are installed, there arise different methods to provide drainage that may also affect air leakage through the assembly. This in turn may give rise to the formation of condensation along the window at the sill or along the window sash and glazing panels. Hence there is a need to determine if, under cold weather conditions, specific interface details that incorporate sill pans provide potential for condensation on the window components in which air leakage paths may be prominent at the sill or else...

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