WUFI Pro Research Articles

Impact of diffuse solar radiation on HAM simulation accuracy

Advance in the numerical simulation models brings higher need for more accuracy outdoor boundary conditions - climate data sets. With influence of the urban heat islands, measured climate on the meadows, far from pawed surfaces creates uncertainty in the simulation. Another problem is the modelling of solar radiation impact on the surface temperatures. Solar radiation heats up the surface of the structure and increase the speed of vapor transport. To obtain correct results, global and diffuse solar radiation is needed in the HAM software. In this paper, influence of the diffuse part of solar radiation is analyzed. As it would be shown, correct modeling of the solar radiation, both global and diffuse is very important to reach good precision. This analysis is done in software WUFI Pro and compared with the experimental measurement of the wooden wall fragments.

Hygrothermal assessment of internally insulated brick wall based on numerical simulation

Massive walls exposed to external climate are characterized by low levels of thermal insulation. Unfortunately in many cases, due to the historic character of the building, the only possible way to improve their thermal insulation is the use of internal insulation. However, such solutions are associated with the risk of frost damage, mould growth or interstitial condensation. Calculations regarding the occurrence of these risks require complex calculation methods. Therefore, in the present work, the evaluation of the hygrothermal behavior of the internally insulated solid brick wall was performed based on the numerical simulations using the program WUFI Pro. Various material solutions of internal insulations, based on both synthetic and natural materials, were compared. The focus was on a particularly sensitive interface between the insulation and the original wall

Influence analysis of climate data time-step on the accuracy of HAM simulation

Scientific research in the area of building simulations has a great potential and it is continuously developing and advancing. Computer simulations are helpful in many areas of Civil Engineering, such as energy demand, moisture transport, thermal comfort, ventilation etc. Climate data measured by experimental weather station are analyzed in this article. Weather station is located within the University campus and data recorded with a short are used in a non-steady heat-air-moisture simulation. Climate parameters differences caused by the various averaging periods are shown. This differences are also analyzed in term of outdoor surface temperatures calculated with WUFI Pro simulation software.

屋上緑化の UHI 緩和効果に関する研究 人工芝と天然芝の日射反射性状実測と Wufi Pro による数値的検討

屋上緑化の UHI 緩和効果に関する研究 人工芝と天然芝の日射反射性状実測と Wufi Pro による数値的検討

超高断熱・高気密住宅の室内熱・湿気性状と冷・暖房・換気負荷削減に関する研究 (その2) WUFI Pro による PCM 天井材の実測性状再現と負荷平準化効果の検討

超高断熱・高気密住宅の室内熱・湿気性状と冷・暖房・換気負荷削減に関する研究 (その2) WUFI Pro による PCM 天井材の実測性状再現と負荷平準化効果の検討

Numerical models performance to predict drying liquid water in porous building materials: Comparison of experimental and simulated drying water content profiles

AbstractA practical way to evaluate drying in porous building materials is through environmental conditioning drying curve where drying is influenced by external factors such as environmental conditions and by the material properties. However, attaining drying curves can be an extremely slow process, which can be unsuited with the schedule and the available resources. This work describes the drying process in porous building materials using the simulation tool “TRHumidade” for the determination of water content profiles inside those materials and comparing with the well-known simulation tool “WUFI Pro” and experimental results obtained by gamma ray. One of the main goals is to validate the use of TRHumidade and evaluate the better tool (TRHumidade vs. WUFI Pro) to describe liquid phase drying processes, to evaluate if the water content potential describes better the drying phenomenon. The numerical results obtained with TRHumidade and WUFI simulation tools are similar to the experimental ones obtained by ...

Impact of future climates on the durability of typical residential wall assemblies retrofitted to the PassiveHaus for the Eastern Canada region

Attention to the global warming has influenced many aspects of human activities. Worldwide effort toward energy consumption reduction in building sector is one of the areas affected by climate change. Building regulations demand the building construction industry to be more energy efficient. Studies have been carried out on the thermal performance of energy efficient buildings under future climates, while studies on the durability of energy efficient building envelopes over future climates are limited. This study assesses the impact of future climates on the durability of typical Canadian residential wall assemblies retrofitted to the PassiveHaus over the current, 2020, 2050, and 2080 climatic conditions for Montreal. The durability performance is evaluated in terms of the frost damage risk of bricks and the biodegradation risk of plywood sheathing through simulations using WUFI Pro program. The future weather files are generated based on weather data recorded at the Montreal International Airport weather station using General Circulation Model HadCM3 based on the A2 emission scenario by the Intergovernmental Panel on Climate Change. This study concludes that upgrading wall assemblies to the PassiveHaus recommended level would increase the frost damage risk of bricks, however, this risk would decrease under 2080 climatic conditions. While the decay risk of the plywood sheathing would decrease, the mould growth risk defined by RHT criteria would increase over future climates. Under future climates, mould growth risks of the plywood defined by the mould growth index exist only when rain leakage is introduced and would likely decrease for the double-stud assembly.

Methods to determine whole building hygrothermal performance of hemp–lime buildings

Hemp–lime is a potentially useful building material with relatively low embodied energy and moderate-to-good thermal performance, coupled with good moisture buffering capacity. However, some uncertainty remains with regards to its in-situ thermal performance and the capability of building energy simulation tools to accurately predict envelope performance and subsequent energy demand of buildings constructed of such vapour-active materials. In this paper we investigate the hygrothermal performance of buildings with walls constructed from hemp–lime. Component-level moisture buffering simulation employing the EnergyPlus simulation tool is found to be within 18% of Wufi Pro analysis and laboratory measurements. The coarseness of component discretization is shown to effect moisture buffering leading to the observation that finer discretization should be employed to improve EnergyPlus HAMT model accuracy. Whole building simulation of the BESTEST building with hemp–lime components indicates that moisture transport inclusion has a large influence on zone relative humidity but little influence on overall heating and cooling demand. A simple effective-capacitance model is able to represent humidity buffering but is less good at representing the response to sudden moisture loading. An additional resistance parameter is added to the model and an IES-ve simulation using this approach is shown to give a close match to the full hygric simulation.

Nanocomposite materials for rapid-response interior air humidity buffering in closed environments

Three different mesoporous silica (MS) samples were selected as template materials for designing novel, high-performance desiccants to give rapid-response temperature and humidity buffering in closed environments. The aim was to investigate how the functional properties of the MS materials can be tuned to suit differing psychrometric conditions in closed environments, and to inform the design process by conducting sensitivity analysis using building performance simulation software. Their humidity buffering performance was compared with other materials using WUFI Pro v5.1 to conduct numerical hygrothermal simulations. The MS materials had more than two orders of magnitude greater humidity buffering than traditional interior building materials (e.g. painted gypsum plaster) due to their high vapour storage capacity and high dynamic vapour sorption (DVS) response rates. Analysis showed that the gradient of the w 50–w 80 portion of the absorption branch isotherm is the most sensitive parameter when using the hygrothermal numerical model as a design tool for materials tuning.

Building Materials in the Operational Phase

SummaryHow sustainable are the various building materials, and what are the criteria for assessment? The scope of this article is to explore in what ways responsible and conscious use of materials can yield environmental benefits in buildings. In particular, it discusses how material properties related to thermal and hygroscopic mass can be utilized for achieving energy efficiency and good indoor air quality, and how these gains can be included into the context of life cycle assessment (LCA).A case study investigates and compares carbon impacts related to three design concepts for an exterior wall: (A) concrete/rock wool; (B) wood studs/wood fiber; and (C) wood studs/hemp lime. The thermal performance of concepts B and C are modeled to comply with concept A regarding both thermal transmittance (U‐value) and dynamic heat flow (Q24h) using the design tool WUFI Pro. An environmental cost‐benefit analysis is then accomplished in four steps, regarding (1) manufacturing and transport loads, (2) carbon sequestration in plant‐based materials and recarbonation in concrete/lime, and (3 and 4) potentially reduced operational energy consumption caused by heat and moisture buffering. The input data are based on suggested values and effects found in the literature.The summarized results show that wall A has the highest embodied carbon and the lowest carbon storage and recarbonation effects, whereas wall C2 has the lowest embodied carbon and the highest carbon storage and recarbonation effects. Regarding buffering effects, wall A has the highest potential for thermal buffering, whereas wall C has the highest potential for moisture buffering.

Transient numerical and physical modelling of temperature profile evolution in stabilised rammed earth walls

Three established stabilised rammed earth (SRE) mix types (433, 613, 703) were identified for analysis, in the form of 300-mm thick test walls, by being subjected to different static air temperature and relative humidity differentials. The predictive numerical model outputs from WUFI Pro v4.1 hygrothermal simulations displayed good accuracy when validated against experimental data from physical modelling conducted using test walls in a climatic simulation chamber. The wall temperature profile evolution and resultant steady state gradients were very similar regardless of mix type indicating that the majority of the wall remained relatively dry. Unless liquid water is present, the thermal resistance and heat capacity of these materials does not change sufficiently to make significant differences to temperature profile evolution regardless of soil mix type. Little scope exists to intelligently modify the ability of SRE walls to absorb and store heat energy simply by manipulation of particle size distribution (PSD) and the resultant bulk density/void ratio relationships, under these conditions. Only the outer layers of the walls appear to interact with moisture in the air, and the predicted transient responses indicate that significant potential exists to intelligently modify the ability of SRE walls to absorb, store and release moisture vapour from the surrounding air simply by manipulation of PSD and the resultant bulk density/void ratio relationships.

Recent developments in the NSU Wankel engine : W. Fröde, (James Clayton Lecture), Inst. Mech. Engrs., Proc. Automob. Div., 180, Part 2A (1965–1966)

Attention to the global warming has influenced many aspects of human activities. Worldwide effort toward energy consumption reduction in building sector is one of the areas affected by climate change. Building regulations demand the building construction industry to be more energy efficient. Studies have been carried out on the thermal performance of energy efficient buildings under future climates, while studies on the durability of energy efficient building envelopes over future climates are limited. This study assesses the impact of future climates on the durability of typical Canadian residential wall assemblies retrofitted to the PassiveHaus over the current, 2020, 2050, and 2080 climatic conditions for Montreal. The durability performance is evaluated in terms of the frost damage risk of bricks and the biodegradation risk of plywood sheathing through simulations using WUFI Pro program. The future weather files are generated based on weather data recorded at the Montreal International Airport weather station using General Circulation Model HadCM3 based on the A2 emission scenario by the Intergovernmental Panel on Climate Change. This study concludes that upgrading wall assemblies to the PassiveHaus recommended level would increase the frost damage risk of bricks, however, this risk would decrease under 2080 climatic conditions. While the decay risk of the plywood sheathing would decrease, the mould growth risk defined by RHT criteria would increase over future climates. Under future climates, mould growth risks of the plywood defined by the mould growth index exist only when rain leakage is introduced and would likely decrease for the double-stud assembly.