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1 – 10 of 16Aitor Erkoreka, Ivan Flores-Abascal, Cesar Escudero, Koldo Martin, Jose Antonio Millan and Jose Maria Sala
Understanding the dynamic hygrothermal behavior of building elements is very important to ensure the optimal performance of buildings. The Laboratory for Quality Control in…
Abstract
Purpose
Understanding the dynamic hygrothermal behavior of building elements is very important to ensure the optimal performance of buildings. The Laboratory for Quality Control in Buildings of the Basque Government tested a flat roof designed by a construction company that developed a building to be constructed using prefabricated modules. This is a five to eight floor building with ventilated façade and a flat roof covered by gravel with the possibility of changing it to a green cover. The paper aims to discuss this issue.
Design/methodology/approach
The interest of this research was threefold. The first objective was to accurately test, under real dynamic weather conditions, the roof design in a PASLINK test cell to obtain the U-value and the thermal capacitance of the different roof layers, and of the roof as a whole, through the precise calibration of resistance-capacitance mathematical models of the roof. Based on the parameters and experimental information of these calibrated models, a second goal was to calibrate and validate a Wufi model of the roof.
Findings
This second calibrated model was then used to simulate the dynamic hygrothermal behavior of the roof, obtaining the roof’s hourly thermal demand per square meter for a whole year in different locations considered in the Spanish Building Code. These simulations also permitted the authors to study the risk of condensation and mold growth of the tested component under different climatic conditions.
Originality/value
The successful combination of the PASLINK method to calibrate the Wufi hygrothermal model is the main novelty of this research.
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Mohammadjavad Mahdavinejad, Kavan Javanroodi and Leyli Hashemi Rafsanjani
The purpose of this paper is to investigate moisture problems and defects which have been caused by condensation in historic buildings. Emphasis has been put on finding…
Abstract
Purpose
The purpose of this paper is to investigate moisture problems and defects which have been caused by condensation in historic buildings. Emphasis has been put on finding condensation possibility on the external walls and inside temperature and humidity.
Design/methodology/approach
A third-part study including survey method to identify moisture problems and exhaustion, then determining indoor and outdoor temperature and relative humidity in a two-part survey within four days periods, and finally computer modeling and simulation to finding condensation possibility in the building walls by WUFI and THERM software.
Findings
Results indicated that the case study has serious defects and almost 7.5°C differences (Δt) and about 6 percent relative humidity differences (Δh) between indoor and outdoor temperature, and from analyzing computer simulations, condensation risk occurrence between wall layers is witnessed. Also this study shows that some climatic methods applied by traditional architects despite enhancing thermal comfort have caused damages and defects to the building envelope and structure. In this paper, the authors suggest a method to reduce condensation possibility by active ventilation for reducing temperature differences.
Originality/value
While there is a lock of technical researches and investigations about architectural heritages conservation, this study tries to perform a technical research and filling the gaps in this subject area.
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J.M.P.Q. Delgado, V.P. de Freitas, A.S. Guimarães and C. Ferreira
Crawl space ventilation became essential to avoid moisture damage. Historical houses with wood floor and crawl spaces unventilated correctly often face problems of biological…
Abstract
Purpose
Crawl space ventilation became essential to avoid moisture damage. Historical houses with wood floor and crawl spaces unventilated correctly often face problems of biological degradation. This paper seeks to address these issues.
Design/methodology/approach
In this work a case study of the Egas Moniz museum house, in Estarreja, Portugal, with different building pathologies, such as biological degradation and development of micro‐organisms and fungi, is presented. An experimental campaign was carried out with continuous monitoring of the relative humidity and temperature, to validate the real climatic conditions in the crawl spaces. Additionally, the authors analyse the treatment technologies used in the past and the characteristics of the rehabilitation solutions in order to control the hygrothermal behaviour. Simultaneously, numerical simulation was done using the software tool WUFI‐2D to simulate the hygrothermal building behaviour and a sensitivity study of parameters used was done.
Findings
The in‐situ experimental results showed that high values of relative humidity imply biological degradation of the wood floor and the numerical and analytical models used showed the same tendency. The numerical results showed the importance of crawl spaces with a good ventilation to avoid mould growth and, also, suggested that controlled mechanical ventilation is preferable to strongly continuous mechanical ventilation in this type of spaces. The experimental study shows that the continuous functioning of a ventilation system may lead to the occurrence of interior condensation, so a hygro‐regulated system is thus essential to control unwanted condensation, with an appropriate functioning criterion.
Practical implications
In accordance with the numerical and experimental results, the authors proceeded to the implementation of a hygro‐regulated system to ventilate the crawl spaces of the Egas Moniz museum house.
Originality/value
This paper presents a new proposed intervention methodology, in crawl spaces, to avoid mould growth, based on an extraction controlled by a hygro‐regulated ventilator.
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The surface temperature of the sub-roof beneath the ventilation layer and the tiles is one of the most important factors for the hygrothermal performance of pitched roofs. The air…
Abstract
Purpose
The surface temperature of the sub-roof beneath the ventilation layer and the tiles is one of the most important factors for the hygrothermal performance of pitched roofs. The air layer between tiles and sub-roof and the air exchange with the outdoor air influence the heat transfer and therefore affect the moisture level inside the roof construction. The paper aims to discuss these issues.
Design/methodology/approach
This paper provides the results of a research project performed at Fraunhofer-Institute for Building Physics, based on field test results. The investigations analyze the thermal behavior of different vented and ventilated roof constructions.
Findings
It was found that for a detailed model with roof cladding and ventilated air layer normally too many parameters are unknown. For that reason a simplified approach was set up, especially to consider the radiation exchange between the tiles and the underlay as well as the effects of the ventilation.
Originality/value
Now, effective surface transfer parameters can substitute both cladding and air layer in the simulation, while the approach still provides a high accordance with the measured values. The paper provides characteristic values for different roofing situations to simulate ventilated roofs by means of hygrothermal simulation in a simplified way.
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This article reviews the development of low energy and sustainable housing in the UK and Germany. It illustrates that despite their close geographical proximity substantially…
Abstract
This article reviews the development of low energy and sustainable housing in the UK and Germany. It illustrates that despite their close geographical proximity substantially different approaches have been applied in the two countries in the pursuit of an energy efficient, domestic built environment.
The article describes and compares the German Passivhaus and the UK Code for Sustainable Homes, both important drivers for low energy housing. It also relates them to two project examples, the ‘Energieautarkes Haus’ (energy independent house) in Freiburg and the BeDZED project near London.
A main conclusion from the article is that Germany has developed with the Passivhaus a design concept that holds a considerable potential to reduce the energy consumption of the UK housing sector, and points out the surprisingly limited uptake so far. It however also emphasises the ability of the UK to apply a holistic building design approach, and points out that the UK has developed with BREEAM and the Code for Sustainable Homes a framework that directs the flow of activity in the pursue of buildings with a low environmental impact.
Finally, the article emphasises the need for better collaboration between different countries.
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The residential sector in Ireland accounted for 25 per cent of energy related CO2 emissions in 2016 through burning fossil fuels, a major contributor to climate change. In support…
Abstract
Purpose
The residential sector in Ireland accounted for 25 per cent of energy related CO2 emissions in 2016 through burning fossil fuels, a major contributor to climate change. In support of Ireland’s CO2 reduction targets, the existing housing stock could contribute greatly to the reduction of space-heating energy demand through retrofit. Approximately 50 per cent of Ireland’s 2m dwellings pre-date building regulations and are predominantly of cavity and solid wall construction, the performance of which has not been extensively investigated at present. Although commitment to thermal upgrade/retrofit of existing buildings may increase under future government policies, the poor characterisation of actual thermal performance of external walls may hinder the realisation of these targets. Thermal transmittance (U-values) of exterior walls represents a source of uncertainty when estimating the energy performance of dwellings. It has been noted in research that the standard calculation methodology for thermal transmittance should be improved. Implementing current U-value calculation methods may result in misguided retrofit strategies due to the considerable discrepancies between in situ measurements and calculated wall U-values as documented in the case studies carried out in this research. If the method of hygrothermal analysis were to be employed as a replacement for the current standard calculation, it could have significant implications for policy and retrofit decision making. The paper aims to discuss this issue.
Design/methodology/approach
This research project analysed a case study situated in Dublin, Ireland. The case studies offer an account of the in situ thermal transmittance of exterior walls and link these to hygrothermally simulated comparisons along with more traditional design U-values.
Findings
The findings of this research identify discrepancies between in situ and design U-values, using measurement, hygrothermal simulation and standard method U-value calculations. The outcomes of the research serve as an introduction to issues emanating from a larger research project in order to encourage researchers to understand and further explore the topic.
Originality/value
It has previously been highlighted that moisture content is linked to the increase in thermal conductivity of building materials, thus reducing the thermal effectiveness and increasing the elemental U-value. Therefore, it is vital to implement reliable prediction tools to assess potential thermal performance values. This paper presents the findings of a critical instance case study in Dublin, Ireland in which an existing west facing external wall in a semi-detached dwelling was analysed, simulated and measured to verify the elemental wall assembly and quantify thermal transmittance (U-value) incorporating the major criteria required for building performance simulation.
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Sara Stingl de Freitas and Vasco Peixoto de Freitas
The purpose of this paper is to present a case study of cracks on external thermal insulation composite systems (ETICS) along the thermal insulation joints and the information…
Abstract
Purpose
The purpose of this paper is to present a case study of cracks on external thermal insulation composite systems (ETICS) along the thermal insulation joints and the information available on the building pathology catalogue – PATORREB. The aim is to establish the methodology to study the cause of the pathology observed on a building which is located on the interior of Portugal based on in situ probing together with the analysis of hygrothermal and mechanical behaviour.
Design/methodology/approach
An in situ analysis was performed to assess the causes. The hygrothermal dynamic behaviour of the wall was analysed with a numerical simulation advanced tool considering the climatic conditions, the characteristics of the thermal insulation plates as well as the support and finishing layer properties. Moreover, a qualitatively analysis of the mechanical behaviour, based on the bonding process, thermal insulation and exterior rendering properties was performed.
Findings
It was concluded that the insulation properties – thermal expansion coefficient and stiffness, the thermal expansion coefficient of the exterior rendering, together with adverse climatic conditions were critical for the appearance of cracks along the plate joints, particularly with spot bonding. The expansion and retraction stresses and the restrained movements of the components can result in bending moments, especially when the insulation material has a high stiffness value, which will create the crack on the rendering system.
Originality/value
A combination between a hygrothermal and mechanical analysis of an ETICS pathology concerning the appearance of cracks with a subsequent integration into a building pathology catalogue.
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Césaire Hema, Philbert Nshimiyimana, Adamah Messan, Abdou Lawane and Geoffrey Van Moeseke
Appropriate thermal properties of walls can lead to the improvement of the indoor environment of buildings especially in countries with low energy availability such as Burkina…
Abstract
Purpose
Appropriate thermal properties of walls can lead to the improvement of the indoor environment of buildings especially in countries with low energy availability such as Burkina Faso. In order to benefit from these advantages, the thermal properties must be properly characterized. This paper investigates the impact of the design of single- and double-layer walls based on compressed Earth blocks (CEB) on the risk of indoor overheating.
Design/methodology/approach
First a building has been used as a tool to measure climate data. Then, a software program was used to define an accurate thermal model. Two indices were defined: weighted exceedance hour (WEH) related to the risk of overheating and cyclic thickness (ξ) related to the thermal properties of the walls. The aim is to define the appropriate values of ξ which minimized the WEH. The study also assesses the sensitivity of these thermal properties to occupancy profiles.
Findings
The results indicate the arrangements of the thermal properties that can promote comfortable environments. In single-layer wall buildings, ξ = 2.43 and ξ = 3.93 are the most suitable values to minimize WEH for the room occupied during the day and night, respectively. If a double-layer wall is used, ξ = 1.42 and CEB layer inside is the most suitable for the room occupied during the day, while ξ = 2.43 and CEB outside should be preferred in the case of a room with night occupancy profile.
Originality/value
The findings indicate that occupation patterns at room scale should be systematically considered when dealing with wall design in order to improve the thermal comfort.
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Sofie Pelsmakers, Evy Vereecken, Miimu Airaksinen and Cliff C.A. Elwell
Millions of properties have suspended timber ground floors globally, with around ten million in the UK alone. However, it is unknown what the floor void conditions are, nor the…
Abstract
Purpose
Millions of properties have suspended timber ground floors globally, with around ten million in the UK alone. However, it is unknown what the floor void conditions are, nor the effect of insulating such floors. Upgrading floors changes the void conditions, which might increase or decrease moisture build-up and mould and fungal growth. The purpose of this paper is to provide a review of the current global evidence and present the results of in situ monitoring of 15 UK floor voids.
Design/methodology/approach
An extensive literature review on the moisture behaviour in both uninsulated and insulated suspended timber crawl spaces is supplemented with primary data of a monitoring campaign during different periods between 2012 and 2015. Air temperature and relative humidity sensors were placed in different floor void locations. Where possible, crawl spaces were visually inspected.
Findings
Comparison of void conditions to mould growth thresholds highlights that a large number of monitored floor voids might exceed the critical ranges for mould growth, leading to potential occupant health impacts if mould spores transfer into living spaces above. A direct comparison could not be made between insulated and uninsulated floors in the sample due to non-random sampling and because the insulated floors included historically damp floors. The study also highlighted that long-term monitoring over all seasons and high-resolution monitoring and inspection are required; conditions in one location are not representative of conditions in other locations.
Originality/value
This study presents the largest UK sample of monitored floors, evaluated using a review of current evidence and comparison with literature thresholds.
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