scholarly journals Improving the Accuracy of a Hygrothermal Model for Wood-Frame Walls: A Cold-Climate Study

Buildings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 236
Author(s):  
Charles R. Boardman ◽  
Samuel V. Glass
Keyword(s):  
Field Study ◽  
Material Property ◽  
Oriented Strand Board ◽  
Field Measurements ◽  
Cold Climate ◽  
Latex Paint ◽  
Kraft Paper ◽  
Humidity Measurements ◽  
Wood Frame ◽  
Improved Model

A one-dimensional transient hygrothermal model was used to simulate eight different wood-frame wall assemblies. Simulations were compared with measured results from a two-year field study exploring the effects of exterior insulation on wall moisture performance in a cold-climate. The field study documented the moisture content, temperature, and relative humidity measurements in wall assemblies using oriented strand board (OSB) sheathing. Simulations were performed using generic design input values as well as input values based on measurements or sensitivity analysis. Laboratory material property measurements informed the choice of material property values in the improved model for OSB, asphalt-coated kraft paper, and interior latex paint. Simulations using improved input values typically agreed with field measurements within measurement error. The most significant model improvements were all related to vapor permeance. The vinyl siding used an effective permeance much lower than typically recommended. However, both the extruded polystyrene insulation and the asphalt-coated kraft paper facing on the cavity fiberglass insulation had higher permeance than literature values.

PERSIAN GARDENS IN COLD AND DRY CLIMATE: A CASE STUDY OF TABRIZ’S HISTORICAL GARDENS

2016 ◽  
Vol 10 (3) ◽  
pp. 193
Author(s):  
Ahad Nejad Ebrahimi ◽  
Farnaz Nazarzadeh ◽  
Elnaz Nazarzadeh
Keyword(s):  
Comparative Study ◽  
Water Supply ◽  
Field Study ◽  
Cold Climate ◽  
Natural Substrate ◽  
Garden Design ◽  
Climate Conditions ◽  
North West ◽  
Special Expertise

Throughout history, gardens and garden designing has been in the attention of Persian architects who had special expertise in the construction of gardens. The appearance of Islam and allegories of paradise taken from that in Koran and Saints’ sayings gave spirituality to garden construction. Climate conditions have also had an important role in this respect but little research has been done about it and most of the investigations have referred to spiritual aspects and forms of garden. The cold and dry climate that has enveloped parts of West and North West of Iran has many gardens with different forms and functions, which have not been paid much attention to by studies done so far. The aim of this paper is to identify the features and specifications of cold and dry climate gardens with an emphasis on Tabriz’s Gardens.  Due to its natural and strategic situation, Tabriz has always been in the attention of governments throughout history; travellers and tourists have mentioned Tabriz as a city that has beautiful gardens. But, the earthquakes and wars have left no remains of those beautiful gardens. This investigation, by a comparative study of the climates in Iran and the effect of those climates on the formation of gardens and garden design, tries to identify the features and characteristics of gardens in cold and dry climate. The method of study is interpretive-historical on the basis of written documents and historic features and field study of existing gardens in this climate. The results show that, with respect to natural substrate, vegetation, the form of water supply, and the general form of the garden; gardens in dry and cold climate are different from gardens in other climates.

scholarly journals Stochastic Simulation of Mould Growth Performance of Wood-Frame Building Envelopes under Climate Change: Risk Assessment and Error Estimation

Buildings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 333
Author(s):  
Lin Wang ◽  
Maurice Defo ◽  
Zhe Xiao ◽  
Hua Ge ◽  
Michael A. Lacasse
Keyword(s):  
Climate Change ◽  
Risk Assessment ◽  
Error Estimation ◽  
Ventilation Rate ◽  
Climatic Conditions ◽  
Cold Climate ◽  
Mould Growth ◽  
Frame Building ◽  
Wood Frame ◽  
Water Tightness

Previous studies have shown that the effects of climate change on building structures will increase the mould growth risk of the wood-frame building envelope in many circumstances. This risk can be controlled by wind-driven rain deflection, improving water tightness of the exterior facade, and improving cladding ventilation. However, the effectiveness of these risk mitigation strategies are subject to various uncertainties, such as the uncertainties of wall component properties and micro-climatic conditions. The objective of this paper is to apply stochastic hygrothermal simulation to evaluate the mould growth risk of a brick veneer-clad wood-frame wall with a drainage cavity under historical and future climatic conditions of Ottawa, a Canadian city located in a cold climate zone. An extensive literature review was conducted to quantify the range of stochastic variables including rain deposition factor, rain leakage moisture source, cladding ventilation rate and material properties of brick. The randomised Sobol sequence-based sampling method, one of the Randomized Quasi-Monte Carlo (RQMC) methods, was applied for risk assessment and error estimation. It was found that, under the climatic condition of Ottawa, limiting the amount of wind-driven rain to which walls are subjected is a more robust mitigation measure than improving cladding ventilation in controlling mould growth risk, the improving of water tightness of exterior façade is not as robust as wind-driven rain deflection and cladding ventilation, however, the reduction of rainwater penetration can reduce the mould growth risk at different levels of rain deposition factor and cladding ventilation rate.

Foam Insulation Behavior in Void Space Under Fire Conditions

2014 ◽  
Author(s):  
Andrew Kurzawski ◽  
Ofodike A. Ezekoye
Keyword(s):  
Oriented Strand Board ◽  
Construction Materials ◽  
Experimental System ◽  
Small Scale ◽  
Void Space ◽  
Gypsum Board ◽  
Space Construction ◽  
Smoke Detectors ◽  
Wood Frame ◽  
Frame Construction

A fire contained within a room can spread into void spaces in the walls and ceiling through penetrations in the material that lines the compartment. Few studies have looked at how a room and contents fire transitions to a structural fire. One of the active areas of fire research is the coupling of the fire to the structure. Lightweight wood frame construction represents the majority of residential construction in the U.S. The construction details and choice of materials will affect the overall fire resistance of the structure. Because of the relative lack of knowledge on the fire penetration into wall spaces, this research examined how fire might penetrate into the void spaces of wood framed structures. In the U.S.A., a critical barrier to the penetration of hot gas products into void spaces is provided by the gypsum-board skin of the compartment. For most compartments, there are many penetrations within the compartment’s gypsum-board skin. Common potential access points include security system wiring (e.q. smoke detectors and cameras), ventilation fixtures, light switches, and electrical outlets among others. A hole in the gypsum may create opportunities for void space ignition. One of the purposes of this work is to develop a small scale testing system to characterize fire driven flow and heat transfer into a void space. With such an apparatus, one can rapidly identify materials that are prone to igniting for a given leakage geometry and fire size. Common materials found in void spaces include wooden structural members, plywood/oriented strand board, a variety of insulation types, and vapor barriers. This study discusses the characteristics of the small scale experimental system and preliminary tests on a range of void space construction materials.

scholarly journals Effect of Zeolite on Shrinkage and Crack Resistance of High-Performance Cement-Based Concrete

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3773
Author(s):  
Nguyen Cong Thang ◽  
Nguyen Van Tuan ◽  
Keun-Hyeok Yang ◽  
Quoc Tri Phung
Keyword(s):  
Particle Size ◽  
Crack Resistance ◽  
High Performance ◽  
Autogenous Shrinkage ◽  
Shrinkage Strain ◽  
Shrinkage Behaviour ◽  
Proposed Model ◽  
Zeolite Content ◽  
Humidity Measurements ◽  
Improved Model

This study examined the effectiveness of zeolite addition to reduce the autogenous shrinkage of high-performance cement-based concrete (HPC). The zeolites were replaced up to 15% of the cement content by weight and their mean particle size varied from 5.6 to 16.7 µm. To evaluate the crack resistance of HPC containing zeolites, the ring tests and internal relative humidity measurements were performed at different ages. The compressive strengths were determined at 3, 7, 28 and 90 days of curing. Test results confirmed that the addition of zeolite was promising and favourable in enhancing the compressive strength, crack resistance and reducing the autogenous shrinkage of HPC due to synergistic pozzolanic and internal curing effects. The autogenous shrinkage tended to decrease with the increase in zeolite content and its particle size. In addition, the extent of the autogenous shrinkage development at the early ages decreased with higher zeolite content replaced. Furthermore, to predict the autogenous shrinkage of HPC containing zeolite, an improved model has been proposed, in which the conventional ultimate autogenous shrinkage strain and time function were modified by introducing new parameters accounting for the zeolite content and its particle size. It appeared that the proposed model was able to capture the autogenous shrinkage behaviour of HPC with or without zeolite, while the fib 2010 model underestimated the autogenous shrinkage of HPC containing less than 10% zeolite replacement.

scholarly journals Analysis of causes of the end of service life of a spray polyurethane foam and polyurea roof

2020 ◽  
Vol 172 ◽  
pp. 15002
Author(s):  
Targo Kalamees ◽  
Simo Ilomets ◽  
Mattias Põldaru ◽  
Paul Klõseiko ◽  
Urve Kallavus ◽  
...  
Keyword(s):  
Service Life ◽  
Polyurethane Foam ◽  
Field Measurements ◽  
High Water ◽  
Climatic Conditions ◽  
Water Vapour Pressure ◽  
Hygrothermal Performance ◽  
Durability Prediction ◽  
Humidity Measurements ◽  
Term Performance

Spray polyurethane foam (SPF) roofs are widely used in North America. Much fewer usage examples and experience can be found in Northern European cold climatic conditions. This study analyses hygrothermal performance and the reasons for the roof’s degradation and end of service life of an SPF and polyurea roof. The service life of the roof is over and major reconstruction is needed eight year after construction. The current study uses field measurements included onsite temperature and humidity measurements and extensive surveying, the roof was opened from several locations and test samples were taken for laboratory tests. The influence of UV radiation on the loss of adhesion was tested. Solar radiation quickly degraded the top surface of the in-situ sprayed polyurethane foam insulation causing a weak connection between the foam layers. Due to mechanically damaged and UV degraded polyurea roofing, water has leaked into the SPF. The water inside or below the foam evaporated during sunny days and broke the adhesion of different foam layers. Larger foam blisters were observed on the upper part of the insulation caused by high water vapour pressure. This is considered the most realistic cause of separation of the SPF layers. The analyse of hygrothermal performance, service life, and durability prediction should be included into the design process, especially for structures with small or without long term performance experience.

Moisture conditions in well-insulated wood-frame walls. Simulations, laboratory measurements and field measurements

2015 ◽  
Vol 10 (3) ◽  
pp. 232-244 ◽  
Author(s):  
Lars Gullbrekken ◽  
Stig Geving ◽  
Berit Time ◽  
Inger Andresen ◽  
Jonas Holme
Keyword(s):  
Field Measurements ◽  
Laboratory Measurements ◽  
Wood Frame ◽  
Moisture Conditions

scholarly journals Hygrothermal performance of highly insulated wood frame walls with air leakage: field measurements and simulations.

2021 ◽  
Author(s):  
Michael J Fox
Keyword(s):  
Simulation Models ◽  
Field Measurements ◽  
Test Facility ◽  
Air Leakage ◽  
Predictive Capacity ◽  
Leakage Field ◽  
Hygrothermal Performance ◽  
Wood Frame ◽  
The University ◽  
Building Engineering

The thesis examines the hygrothermal performance of six types of high thermal resistance (High RSI) wall assemblies during environmental exposure and an air leakage (exfiltration) simulation test. These walls were installed in the Building Engineering Group's test facility (BEG Hut) located at the University of Waterloo. The High-RSI wood-frame walls were assessed by analyzing condensation, mould, and decay risks using the moisture content, temperature, relative humidity and heat flux data collected during the field test. These field-measured data were also used to calibrate one-dimensional WUFI® simulation models for each of the High-RSI assembly for use in future durability assessments using a range of North American climates. Methods were investigated to improve the predictive capacity of these simulation models as well as to increase their utility as a research tool. The design, construction and instrumentation details of the High-RSI study were also documented.

scholarly journals Experimental Study On The Flexural Behavior Of Structural Insulated Headers

2021 ◽  
Author(s):  
Dana Benadova
Keyword(s):  
Oriented Strand Board ◽  
Experimental Testing ◽  
Residential Buildings ◽  
Limit State ◽  
Operating Conditions ◽  
Flexural Behavior ◽  
Design Strength ◽  
Structural Capacity ◽  
Wood Frame ◽  
Flexural Tests

A series of flexural tests were conducted on 18 structural insulated header panels with timber flanges and Oriented Strand Board (OSB) webs to predict their behavior when subject to gravity loading when used in residential and low rise non-residential buildings. The experiments were designed and performed to test full-scale Structural Insulated Panels (SIPs) headers for exterior or interior wall residential construction. The structural adequacy of the header panels of various sizes is investigated in order to meet both strength and serviceability limit-state design requirements per Canadian Standards for timber design. Strength requirements included flexure and shear, while serviceability check included limiting deflection under operating conditions. Results from experimental testing were used to draw conclusions with respect to the structural qualifications for these SIP headers to be "as good as" the structural capacity of conventional wood-frame buildings.

scholarly journals Hygrothermal performance of a massive natural stone masonry wall insulated from the internal side with hemp concrete – field measurements in cold climate

2021 ◽  
Vol 2069 (1) ◽  
pp. 012068
Author(s):  
Markus Pau ◽  
Targo Kalamees ◽  
Urve Kallavus
Keyword(s):  
Large Scale ◽  
Temperature Drop ◽  
Field Measurements ◽  
Masonry Wall ◽  
Cold Climate ◽  
Stone Masonry ◽  
Actual Structure ◽  
Long Period ◽  
Hygrothermal Performance ◽  
Moist Environment

Abstract Improving of exterior walls in historic and traditional buildings is often only possible with interior thermal insulation. The actual structure and material properties of the existing exterior wall are usually the main unknown factors. Therefore, field measurements with small mock-ups are helpful before large-scale renovation. The current study analyses by field measurements the hygrothermal performance of internally insulated massive stone wall. Two different hemp concrete mixes were developed for the insulation. Temperature and humidity conditions were measured periodically over one year period. Results showed a very low drying rate of hemp concrete interior insulation. The external side of hemp concrete insulation will stay moist for a very long period. Temperature of coarse hemp concrete was slightly higher during the cold period. Wooden studs used to install hemp concrete will stay in moist areas for a long period. Temperature drop below 0 °C shows that interior insulation should be durable for freezing-thawing cycles. Drying out of constructional moisture is absolutely necessary for hygrothermal design. Before considering large-scale renovations, it is necessary to further assess the long term durability and performance of hemp concrete in a moist environment. The temperature increase on the interior surface could slightly improve indoor thermal comfort.

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