bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity analysis of hygrothermal performance of wood framed wall assembly under different climatic conditions: the impact of cladding properties
Authors: Aggarwal Chetan , Wang Lin , Defo Maurice , Ge Hua , Junginger Max , Lacasse Michael A
Published: December 2021

One of the parameters that influences the moisture performance of the wood framed wall assembly is the material properties of exterior cladding. The uncertainties of its properties, would result in a range of wall performance. The objective of this study was to investigate the impact of uncertainties in cladding material properties on moisture performance of wood framed wall assembly under different climatic conditions. A wood framed (2×6 wood stud) wall with exterior brick cladding was simulated assuming 1% rain leakage deposited on the exterior side of sheathing membrane. A parametric study was carried out to analyze the impact of the cladding properties on the moisture response of OSB. The simulations were conducted in five different cities located in different climate zones across Canada. The aim was to identify the most influential cladding property on the moisture response of OSB, i.e., mould growth index and moisture content, to the varying cladding properties under different climatic conditions i.e., different cities under historical and future conditions. In general, it was found that liquid diffusivity is the parameter that has the most influence on moisture response of OSB in all the five cities. Also, the significance of this influence varies depending on the climatic conditions.
Case study of fungal growth on newly cast concrete floors
Authors: Kristensen SM , Koch AP , Sheard JK , Thrane U
Published: December 2021

In several cases, the Danish Technological Institute has experienced widespread fungal growth on newly cast concrete floors, with a moisture barrier and floating wooden flooring. The reason for fungal growth is usually due to an inadequate drying period. Existing recommendations require that the relative humidity (RH) of air in equilibrium with the concrete, measured in the middle of the concrete, should not exceed 85-90% RH. In this study, six randomly picked apartments in a newly built apartment complex, were chosen for a case study of fungal growth and moisture on newly cast concrete. The study demonstrates that at least some pecies of fungi can grow very well on newly cast concrete if the surface is dusty and moist. The study also demonstrates that a few samples on the surface will often be representative for the whole floor. The study finds that there is a need to revise the existing guidelines for acceptable moisture content in the concrete before mounting the floor. This might have an impact on the entire building process and/or the design of the floor construction. The study also finds that there is a need for a guideline for measuring moisture and fungal growth on newly cast concrete floors.
Air preheating potential with high Opaque Ventilated Façade under natural and forced convection
Authors: Colinart T , Noel H , Batard M , Fuentes A , Magueresse A , Glouannec P
Published: December 2021

Opaque ventilated façades (OVF) are increasingly used in building envelope because of their positive impact on building energy efficiency. Usually, air flow is driven by natural ventilation. Recently, there were some attempts to drive air flow mechanically to preheat or precool air in combination with HVAC, Heat pump or Latent Heat Thermal Energy Storage (LHTES) systems. In this framework, an experimental real-scale module of an OVF was built (1.9 m width and 3.5 m height). In this study, OVF is tested during autumn under natural and under forced convection by means of ventilator placed at cavity outlet. Inlet air flowrate are changed from day to day or during the day. For each test, temperature, air velocity, air flow rate and thermal flux are monitored at different locations of OVF. Their analysis shows that collector efficiency and amount of collected energy depend mainly on cavity air flow rate. The measurements are compared to simulation results obtained from two thermal models describing OVF: Trnsys Type 1230 and home-developed pseudo 2D. A good agreement is found for air temperature at cavity outlet while differences are observed in opaque layers due to modelling assumptions. Last, sensitivity analysis on two design parameters is carried out.
Determination of the anisotropic thermal conductivity of an aerogel-based plaster using transient plane source method
Authors: Karim A N , Adl-Zarrabi B , Johansson P , Sasic Kalagasidis A
Published: December 2021

Aerogel-based plasters are composite materials with declared thermal conductivities in the range of traditional insulating materials, i.e. 30-50 mW/(m·K). Based on the results from reported field measurements, aerogel-based plasters can significantly reduce the thermal transmittance of uninsulated walls. However, the in-situ measured thermal conductivities have sometimes been higher than the declared values measured in laboratory and in the main direction of the heat flow. Meanwhile, the anisotropic thermal performance of aerogel-based plasters, i.e., deviating thermal performance in the different directions of heat flow, has not been explored yet. The objective of this study is thus to evaluate the anisotropic thermal conductivity of an aerogel-based plaster. This is done in a set of laboratory measurements using the transient plane source method. Six identical and cubic samples with the dimensions of 10×10×10 cm3 were paired two and two, creating three identical sample sets. In total, 360 measurements of thermal conductivity and thermal diffusivity, and 130 measurements for specific heat capacity were conducted. The results indicate a weak anisotropy of less than ±6.5 % between the three directions (x, y, z). Considering the accuracy of the selected measurement technique, better than ±5 %, supplementary measurements using another technique are recommended.
Analysis and comparison of passive and climate-unadapted design in terms of resources, energy demands and thermal comfort by means of building simulation and life cycle assessment
Authors: Mayer A J , Jürgens T
Published: December 2021

The aim of passive design is to respond to the external climate using primarily structural means to achieve a comfortable indoor climate. The use of building technology is an additional measure. This paper compares the demand for resources, primary energy, and thermal and air-hygienic comfort of passive and climate-unadapted designs to determine the most energy-efficient and sustainable design. It also analyses whether user comfort suffers from reduced use of technical building equipment. For this purpose, a representative passive building model is compared with a climate-unadapted one. Comfort, primary and embodied energy are determined and compared by way of a simulation and life cycle assessment. The passive design presents a lower primary energy demand than the climate-unadapted one, even when embodied energy is taken into account. While the requirements of air-hygienic comfort are fulfilled equally in both types of buildings, the passive design displays better thermal comfort. This indicates that energy can be saved by employing a passive design.
A mathematical model for predicting the indoor moisture variation by using moisture buffering theory
Authors: Zu Kan , Qin Menghao
Published: December 2021

Indoor air humidity evaluation plays an of great importance role on the thermal comfort and building energy consumption. The utilization of hygroscopic materials as building materials acts on the indoor air humidity by regulating its humidity fluctuations, and then reduces a certain fraction of energy consumption on the air conditioning systems. Based on the Fick’s law, the physical process inside these hygroscopic materials requires the determinations of hygrothermal properties, which signify the extensive and reiterative experiments. While in many building simulation toolboxes, moisture buffering behavior has been evaluated by either simple approximations or complicated heat and mass model. In this case, we developed a mathematical model about the moisture transport with acceptable solution time and accuracy in terms of the moisture buffer value (MBV) theory. Considering that MBV originally represents the moisture buffering capacity of those hygroscopic materials, we did some mathematical deduction about MBVs under different boundary conditions. Then the definition of time-average MBV has been used, and all the required parameters was obtained from the practical MBV test. By comparing the new moisture buffer value model (MBM) with HAMT model, the results indicated that MBM could provide reasonably accurate prediction for indoor moisture variation.
Experimental analysis of moisture uptake and dry-out in CLT end-grain exposed to free water
Authors: Kalbe K , Annuk A , Ruus A , Kalamees T
Published: December 2021

This paper presents the results of a series of laboratory tests of CLT end-grain moisture uptake and dry-out. We put CLT test details (TDs) in direct water contact from the end-grain edge and then left the TDs to dry for two weeks in the laboratory and in an outside shelter. Half of the TDs had their wet sides attached to another CLT detail. Fibre saturation point was quickly reached in the bottom part of the TDs during the seven-day water contact. A tendency of increasing moisture content (MC) was up to 90 mm from the wet edges, but we did not record MC levels above the critical level at that height. However, MC exceeded critical levels at 60 mm from the water level. The measured water absorption coefficient Aw was 3.51×10−3 kg/m2-s0’5. Drying was negligible for the TDs which were in contact with another CLT detail. Thus, moisture dry-out is very complicated in joints where the CLT end-grain is covered, such as the exterior wall to foundation or intermediate ceiling connection. The dry-out of CLT is not expected in a cold and humid outdoor environment once the CLT end-grain has absorbed moisture even with wet edges exposed to air.
Damage risk analysis of a Timurid heritage located in Iran exposed to outdoor climate change (Ghiassieh school)
Authors: Hedayatnia Hamed , Steeman Marijke , Bossche Nathan Van Den
Published: December 2021

The first step to preserving the historical heritage against global warming effects is finding how this phenomenon affects building material degradation. Due to the vulnerability of Iranian heritage to climate change and lack of proper literature, research on climate change’s impact on Timurid heritage buildings in Iran has been determined as the primary research goal. The study is performed by analysing weather data, HAM simulations, and different damage criteria. This paper aims to find an appropriate method to study climate change’s impact on historical buildings. A Timurid historical school is chosen as a case study to better understand the current climate change effects on building components. The analysis shows that the significantly rising air temperature and wind speed, along with reduced rainfall and humidity, causes a notable decrease in building envelope moisture content in addition to an increase in hydrated salt crystallisation cycles during the studied period. These fluctuations may have played a crucial role in the pathologies that can be observed on site, and their continuation and expansion in the future, as the models have predicted, may lead to irreparable damages to the building.
Effects of climate change on the moisture performance and durability of brick veneer walls of wood frame construction in Canada
Authors: Defo M , Lacasse M A , Wang L
Published: December 2021

The objective of this study was to assess the potential effects of climate change on the moisture performance and durability of red matt clay brick veneer walls of wood frame construction on the basis of results derived from hygrothermal simulations. One-dimensional simulations were run using DELPHIN 5.9 for selected moisture reference years of the 15 realizations of modelled historical (H: 1986-2016) and future (F: 2062-2092) climate data of 12 Canadian cities. The mold growth index at the outer layer of the OSB sheathing panel was used to compare the moisture performance under H and F periods. Results for the base design that meet the minimum requirements of the National Building Code of Canada showed that cities within the interior of the country, characterized by a low annual rainfall, are less likely to develop significant mold growth under H and F periods, whereas cities in coastal areas, characterized by high annual rainfall, present a heightened risk to mold growth under both H and F periods. For cities located on the west coast, a possible solution could be to use a 38-mm ventilated drainage cavity as this measure would help dissipate moisture from within the cavity. On the east coast, apart from using a 38-mm ventilated drainage cavity, other measures aiming at reducing the wind-driven rain deposition (i.e., increasing overhang ratio or the height of the roof) could be introduced. However, the feasibility of such measures needs to be considered in respect to whether these are to be implemented as part of a new building or retrofit of an existing one.
Influence of climate change on the energy performance assessment of NZEB houses
Authors: Janssens A , Vandenbussche E , Van den Brande K , Bracke W , Delghust M
Published: December 2021

The Energy Performance of Buildings (EPB) regulations aim to reduce primary energy use and carbon dioxide emissions of buildings, which are the result of creating a comfortable and healthy indoor environment. In this study, the influence of climate change on the regulatory EPB calculation results is analysed for the Flanders region in Belgium. The results of the analysis may be used by authorities to better define nearly zero energy building (NZEB) requirements today. Meteonorm has been used to simulate future climate change based on IPCC scenarios and urban heat island effect. These future climates have been implemented in a Revit-and Excel-based tool that calculates the stochastic variation of energy performance for six different dwelling typologies, based on the semi-steady state energy use calculation method applied in the regional rating method. Four different packages of measures to achieve NZEB performance (thermal insulation, energy efficient ventilation, renewable energy technologies,…) have been considered. The results for primary energy use, overheating indicator and net energy use for heating and cooling have been analysed. As may be expected, climate change is found to lead to an increase in overheating risk, an increase in cooling energy use, and a decrease in heating energy use in the analysed dwellings. Since in most cases the decrease in heating energy use outweighs the increase in cooling energy use, the total primary energy use decreases in most cases for the 2050 future climate.
Thermal performance of a novel lightweight emergency construction system in different climates
Authors: D’Orazio Marco , Maracchini Gianluca
Published: December 2021

Prefabricated, lightweight construction systems, thanks to their quicker construction processes, cheapness, higher portability, and adaptability, are increasingly proposed all around the world as emergency architectures (after natural disasters, pandemics, etc.), and as affordable housing solutions in countries with increasing housing demand. Due to their low thermal inertia, however, these buildings are often characterized by poor thermal performance in hot climates due to indoor overheating. The possible application of passive cooling measures is often investigated to improve their thermal performance. Among others, cool materials present some advantages in terms of ease of application and costs. However, few studies investigated the impact of this passive strategy on the thermal performance of emergency buildings. For this reason, this work evaluates the impact of cooling materials on the thermal performance of a novel lightweight prefabricated construction system (HOMEDONE) based on the assembly of reinforced-EPS panels. First, a numerical model of an experimental mock-up was created and calibrated on experimental data. Then, the thermal performance of a typical temporary housing solution was numerically evaluated under different climatic locations. Finally, the effectiveness of cooling finishing materials is investigated. The potential of cooling materials in reducing the energy demand for the studied construction system is then highlighted.
A multi-year comparative analysis of green and conventional roof thermal performance under temperate climate conditions
Authors: Gunn P , Gunay H B , Van Geel P J
Published: December 2021

Research suggests that—relative to conventional roofs—green roofs can significantly reduce rooftop heat exchange in moderate climates; however, limited research exists on the performance of green roofs in colder climates. This paper analyzes the comparative performance of two side-by-side roof assemblies: a conventional roof and a green roof located in the temperate climate of Ottawa, Canada. Using two years’ worth of temperature and solar radiation data, we analyze variations in the incremental thermal benefit of the green roof relative to the conventional roof. We discuss factors contributing to these variations, such as precipitation and ambient temperature. Our results indicate that the green roof under investigation reduced thermal transmittance by 31.5% on average across two years. Although the percent benefits were much higher during the summer months, reductions in thermal transmittance were consistently above 7.7% throughout both years, indicating green roofs may be an appropriate alternative to conventional roofs in climates with hot, humid summers and cold, snowy winters.
Hygrothermal performance of a massive natural stone masonry wall insulated from the internal side with hemp concrete – field measurements in cold climate
Authors: Pau Markus , Kalamees Targo , Kallavus Urve
Published: December 2021

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.
Optimization of insulation levels from an environmental perspective: impact of HVAC controls and Personal Comfort Systems
Authors: Landuyt L , Lauwerys S , De Turck S , Steeman M , Van Den Bossche N
Published: December 2021

Today, strict insulation requirements apply. Nevertheless, the inverse correlation of thermal conductivity with insulation thickness leads to decreasing energy savings with increasing insulation packages. Therefore, a balance between potential energy savings and environmental impact due to additional materials using Life Cycle Assessment (LCA) needs to be strived for. This balance is sought for a case study called ‘The Mobble’ i.e. a flexible, modular, and circular building system developed by a student team from Ghent University. Through an iterative design process supported by LCA, comfort and dynamic energy simulations efforts are made to design an energy-efficient and low impact module with an agreeable indoor environment. First, material choices are made based on LCA and the material impact of a 5-module home is calculated. Second, energy calculations are executed in Modelica/Dymola. For this, three possible energy reductions are explored: insulating the building, altering the working regime of the HVAC system and lowering the setpoint temperature while maintaining comfort by using personal comfort systems (PCS). The results support PCS as a possible energy conservation measure and indicate that reducing operational energy does not shift the environmental burden to the additional materials’ production. However, these environmental saving effects decrease as the operational share decreases.
Historic Indoor Microclimate, the role of HVAC in heritage buildings’ restoration: the case of the Palace of Venaria Reale
Authors: Bonora Anna , Fabbri Kristian , Pretelli Marco
Published: December 2021

The paper is aimed to illustrate how the study of the indoor microclimate, supported by the virtual simulation and by the knowledge of the historical evolutions of the building (managerial, usage and architectonical changes over the years), represents a preventive practice which allows to evaluate and predict the interactions between the object and the environment. To do that the authors present a case-study: room 33 in the Palace of Venaria Reale, in Turin, Italy. We have reproduced a virtual building model which presents the same indoor and outdoor microclimatic conditions of the original building. Moreover, we evaluated an alternative scenario that simulates the indoor microclimate of room 33 considering the HVAC systems continuously off. The comparison between the two virtual buildings allowed to estimate the impact of the HVAC system on the preventive conservation of the historical building, of the artefacts and of the occupants’ thermal comfort. Those simulations clarified which indoor microclimatic conditions could be guaranteed by the building itself, after the restoration project of the whole Palace started in 2001.
Circadian winter thermal profiles and thermal comfort in historical housing — field study
Authors: Baborska-Narożny M , Laska M , Fidrów-Kaprawy N , Malyszko M
Published: December 2021

In winter thermally inefficient building envelopes of pre-retrofit historical housing allow for ca. sevenfold higher heat loss from heated apartments than the new built housing in Poland. As a result space heating in pre-retrofit tenements is regarded to be highly energy demanding and costly if the internal temperatures were to be kept on average at standard 20 °C assumed in building regulations. In this field study, carried out in January-March 2020, we investigated circadian thermal profiles and the associated thermal comfort in historical tenements both pre-and post-retrofit. The 16 apartments participating in our research were equipped with heating systems prevalent in Polish urban historical buildings, i.e. solid fuel stoves, electric heating, district-supplied central heating, or individual gas boilers. The former systems provided intermittent local heating while the latter central heating with thermostats. Our research comprised spot check multi-parameter measurements and continuous monitoring of the thermal environment, together with a longitudinal thermal comfort questionnaire survey (N=.2539), energy consumption analysis and semi-structured interviews with the residents. The differences detected in average (12.6°C) and range (up to 5.0°C) of diurnal temperatures did not explain the thermal comfort survey results on individual thermal sensations and preferences. What proved more important for the residents was the time of day when the maximum or minimum temperatures occurred and their perceived control over temperature and the cost associated with heating. Accordingly, we identified a need for further studies investigating the link between domestic thermal comfort and satisfaction with the usability of the heating system and control over the cost of heating.
Assessment of the heat loss coefficient of a renovated historical dwelling using a co-heating test
Authors: Van de Putte S , Himpe E , Nonneman J , Steeman M , Janssens A
Published: December 2021

Twelve quasi-identical almshouses with an architectural-historic value were reno-vated, because of their high energy use, poor indoor comfort and numerous moisture problems. Aerogel plaster was applied for the hygrothermal upgrade of the uninsulated brick walls, while limiting the reduction of living space in these very small houses and keeping the monumental character of the facades in their original state. Several quality assurance tests were executed to evaluate the quality of the renovation of the building envelope and to compare the results with the initial theoretical design calculations. It appeared that the existing materials performed considerably better than the assumed conservative default values. On the other hand, the newly installed insulation materials performed somewhat less than declared, for example due to on-site processing. This resulted in a strong overestimation of the improvement in thermal performance by the renovation works. Field measurements of the existing situation can help to close this gap.
Heating the Dutch housing stock without natural gas
Authors: Koene F G H , Oppenoorth M , Langedijk R
Published: December 2021

This paper studies the level of improvement of building envelopes required to heat the Dutch housing stock using an energy supply without natural gas, such as a district heating network at lower supply temperature or a heat pump. We identified 35 building types to represent the Dutch housing stock of single-family dwellings. A 4R2C building model was used to assess whether the dwellings could be heated at lower supply temperatures after they were renovated according to six renovation packages of different ambition level.
Static and dynamic thermal characterization of facade with mineral foam insulation using a hot-box apparatus
Authors: Gengembre Edouard , Jacquemet Karine
Published: December 2021

Reducing heat loss through the envelope of the building had been an efficient way to save on heating and reduce energy consumption of buildings. In Europe, typical exterior walls need to prevent heat loss during cold weather but more and more allow comfortable temperature condition during the hot season. Indoor comfort in hot seasons is dependent on the thermal transmittance and on its dynamic response during hot days. The study presents guarded hot-box measurements of exterior walls build with insulating masonry and insulation boards made of innovative mineral foam used as an insulation material. The masonry is a composite system of concrete block filled with mineral foam to reduce the thermal transmittance. Insulation boards are made of mineral foam and are added to achieve the overall thermal transmittance targeted. Static and dynamic measurements were performed in order to compare thermal transmittance and decrement delay. The results are compared with those obtained from calculations carried out of the same walls through the application of European standards and a finite volume simulation. Uncertainties of the guarded hot-box measurement and calculation methods are discussed. Results shows that with equivalent U-values, the solution offer higher decrement delay compared to a traditional wall using conventional masonry and polystyrene insulation boards.
Component sequence and thermal mass effects on the transient thermal performance of concrete walls
Authors: Salehpour B , Ghobadi M , Moore T , Ge H
Published: December 2021

The increased requirements of buildings to reduce energy use have highlighted the importance of accounting for all factors that influence energy use in buildings. One consideration that requires further study in the envelope design of concrete-based wall assemblies is the placement of the thermal mass layer. In this study, two thermally massive walls, Insulated Concrete Form (ICF) and tilt-up walls, with the same thermal resistance but different sequencing of layers are investigated. In addition, a wall made of a homogeneous insulation layer with an identical thermal resistance was considered to further investigate the thermal mass effect on the potential for energy savings. Results of the numerical simulations performed using COMSOL Multiphysics® software indicate that, for the transient scenarios investigated, thermal mass can contribute to shifting and dampening peak heating and cooling loads, as well as saving energy. Also, less intense fluctuations were observed in the heat fluxes when considering the ICF wall. Energy savings during the primary seasons (i.e. winters in Montreal and summers in Miami) are found to be marginal but the existence of a thermally massive layer considerably reduced the demands during secondary seasons i.e. summers in Montreal and winters in Miami.
Energy performance analysis of smart wall system with switchable insulation and thermal storage capacity
Authors: Iffa Emishaw , Salonvaara Mikael , Hun Diana
Published: December 2021

The ever-increasing global energy demand and the issues caused by population growth and unsustainable energy resource usages have several environmental and economic impacts. The on-demand capability of dynamic wall systems with switchable insulation systems can contribute toward energy efficiency and reduced electric cost using “building-as-a-battery.” In this paper, the performance of an exterior envelope system that employs a switchable insulation system is investigated. A COMSOL simulation was used to study the envelope performance under three switchable insulation locations in the wall system. The on and off switching cycle included insulating or conducting the exterior, interior, or both sides of the mass wall system. To validate the simulation work, an experimental test was conducted in climate chamber on a 4 × 8 in. wall system with identical wall components used in the COMSOL simulation. Results show a good agreement between the experiment and simulation results. The wall system with switchable insulation placed on the exterior side provided the highest interior inward heat flux when compared with the interior or split insulation. Also, an exterior switchable insulation system in addition to a thermal mass maintained a positive heat flow for more hours when the outdoor temperature was lower than the interior temperature.
Comparing statistical modeling techniques for heat loss coefficient estimation using in-situ data
Authors: Zhang Xiang , Ritosa Katia , Saelens Dirk , Roels Staf
Published: December 2021

The combination of in-situ collected data and statistical modelling techniques proved to be a promising approach in actual building energy performance assessments, such as heat loss coefficient (HLC) evaluation. In this study, based on datasets of co-heating and pseudo-random binary sequence heating tests on a portable site office, the performance of three types of statistical models (i.e. multiple linear regression (MLR), autoregressive with exogenous terms (ARX), and grey-box models) on HLC-determination are examined. It is revealed that a similar HLC estimation outcome (about 115 W/K) is offered by the aforesaid three types of statistical models, but with different confidence intervals (CIs), where the 95% CIs of MLR (±3.1%) and ARX (±2.4%) are relatively narrow and the ones of grey box models are somewhat wider (around ± 9%). Moreover, for the current case study building, with evenly orientation-wise distributed glazed envelope, integrating B-splines into the grey-box model, to characterize the solar aperture (gA) and solar gain dynamics more precisely, imposed insignificant effects on the HLC estimation and corresponding 95% CIs, compared to the grey-box model with a constant gA assumption.
Domestic hot water system in residential buildings: production, distribution and consumption energy loss. Monitoring campaign in two Danish detached houses
Authors: Marszal-Pomianowska Anna , Jensen Rasmus Lund , Pomianowski Michal , Larsen Olena Kalyanova , Jørgensen Scharling Jacob , Knudsen Sofie Sand
Published: December 2021

The share of the energy use for domestic hot water (DHW) in the total energy consumption of buildings is becoming more and more prominent. Depending on the building typology it varies between 20% to 50% of the total energy usage for old and new built single family house, respectively. The aim of this paper is to determine the energy losses in the DHW installation with division between: a) loss at the production point, b) loss in the distribution, and c) loss at the draw-off points using the results of the measurements of DHW consumption in two single family houses connected to district heating grid. The total Eloss for the two houses vary between 17% and 26%. For House 1, the production loss accounts for 8%, the pipe loss for 15% and loss at the draw off points for 3%. Moreover, the results shown that the layout of the house, in particular the placement of the bathrooms with showers or bath tubs has significant impact on the size of the distribution losses.
A probabilistic approach to include the overall efficiency of gas-fired heating systems in urban building energy modelling
Authors: Ritosa K , De Jaeger I , Saelens D , Roels S
Published: December 2021

Urban building energy modelling has an essential role in the estimation of energy demand at urban or neighbourhood scales. However, current modelling methods have limitations in reproducing realistic gross energy usage. Although it is theoretically possible to simulate all components of the heating system in detail, such an extensive approach significantly increases the computational effort, prohibiting a large scale probabilistic analysis. As an alternative, this paper presents a simplified data-driven approach to estimate the overall efficiency for the six most occurring gas-fired heating system configurations in Flemish single-family dwellings. For all configurations, efficiencies of emission, distribution, production, control and storage components are taken into account, of which the efficiency of the production unit is modelled most in detail as it includes the load-dependency. The approach is applied to a sample of 20 dwellings reflecting realistic variation in size, insulation quality and occupancy schedules. For all dwellings and the different heating systems the resulting annual production efficiency, and monthly heating systems’ efficiency as a function of gross energy demand are shown based on the 25th, 50th and 75th percentile.
Quantile regression using gradient boosted decision trees for daily residential energy load disaggregation
Authors: Delcroix B , Sansregret S , Larochelle Martin G , Daoud A
Published: December 2021

The building sector is responsible for approximately one-third of the total energy consumption, worldwide. This sector is undergoing a major digital transformation, buildings being more and more equipped with connected devices such as smart meters and IoT devices. This transformation offers the opportunity to better monitor and optimize building operations. In the province of Quebec (Canada), most buildings are equipped with smart meters providing electricity usage data every 15 minutes. A current major challenge is to disaggregate the different energy use from smart meter data, a discipline called non-intrusive load monitoring in literature. In this work, the aim is to develop and validate a potentially generalizable model for all houses that identifies the daily share of each energy use based on building information, weather data and smart meter data. Input features are selected and ordered using an aggregated score composed of the correlation coefficient, the feature importance given by a decision tree, and the predictive power score. Two modelling methods based on quantile regression are tested: linear regression (LR) and gradient boosted decision trees (GBDT). Compared to ordinary least squares regression, quantile methods inherently provide more robustness and confidence intervals. Both models are trained and validated using separate datasets collected in 8 houses in Canada where metering and sub-metering were performed during a whole year. Results on the test dataset indicate a better performance of the GBDT model, compared to the LR model, with a coefficient of determination of 0.88 (vs. 0.78), a mean absolute error of 6.34 % (vs. 8.89 %) and a maximum absolute error between the actual and predicted values in 95 % of the cases of 17.2 % (vs. 23.1 %).
The ZEB Laboratory: the development of a research tool for future climate adapted zero emission buildings
Authors: Nocente A , Time B , Mathisen HM , Kvande T , Gustavsen A
Published: December 2021

The building sector is responsible for approximately 40 % of the energy consumption and carbon emissions worldwide. Buildings of the future will have to comply not only with stricter energy regulations, but they will also have to face changing climate challenges. To increase the level of interdisciplinary knowledge and to develop and test innovative technology with users, new types of adaptive research facilities are needed. The development of the ZEB Laboratory replies to this need. Developing the building as a research tool has made us focus on 1) a flexible laboratory for tomorrow building design research and 2) making the building itself a climate adapted zero emission building. The laboratory building is realised following the Norwegian ZEB-COM ambition. The development of this research tool has called for an iterative approach with use of partnering and collaborative elements for planning and production. Connected challenges related to e.g. research facility needs, building process, building physics, flexibility of use, energy supply and indoor environment had to be solved through iterations and co-creation processes. This paper presents a modern research tool for climate adaptation and mitigation measures for buildings including stormwater management at site and assesses the development and building process of the laboratory.
The Costs, Benefits and Stakeholder Analysis of an Irish Social Housing Deep Energy Retrofit Case Study
Authors: Colclough Shane
Published: December 2021

This paper analyses the results of a pilot deep energy retrofit (DER) implementation including the financial perspectives of the stakeholders with the aim of assisting DER policy development. The Multiple Beneficiary Analysis (MBA) provides technical and energetic details for a recent 12-unit DER social housing project and quantifies the multiple direct and indirect benefits – e.g. financial, economic and societal to enable a stakeholder (beneficiary) analysis. The analysis is apposite given the urgent need for effective policy development in order to enable the achievement of the low-energy retrofit mandated by the EU. The MBA finds that the stakeholder who benefits most (the tenant) makes no financial contribution to the higher standards and while the Central Exchequer also benefits significantly, the stakeholder who makes the upgrade decision (landlord) is financially dis-incentivised. Given the significant benefits which accrue to the Central Exchequer, there is an opportunity for strategic investment by the government to unlock the benefits of low energy dwellings. This would simultaneously realise ongoing financial benefits, “seed” the capability within industry and crucially increase the knowledge and understanding of low energy dwellings which is necessary to enable widespread adoption. The key finding is that despite potential returns of approximately twice the investment, and the urgent need to retrofit existing buildings, the required DER uptake is unlikely as the decision-makers require financial support to unleash the multiple benefits of energy efficient dwellings. A self-financing support is suggested for the case study for consideration.
Experimental and numerical assessment for HVAC management in an industrial building: a preliminary optimization
Authors: Stamponi E , Lattanzi N , Moretti E
Published: December 2021

COVID-19 emergency has caused major changes in everyday life in the last months, and it also affected the management of buildings. In particular, indoor air quality and ventilation have been considered to play a key role in the spreading of the infection, causing national and international subjects to draw up specific guidelines on ventilation and air recirculation rate in AHUs. The paper deals with the “Loccioni Leaf Lab”, an industrial building that hosts offices and workers operating on test benches. The building features high performance envelope, solar photovoltaic systems, groundwater heat pumps and a high-technology control and monitoring system and it is connected to a thermal and electric smart grid. A validated model of the building, implemented with the software DesignBuilder and EnergyPlus, was used to carry out numerical simulations to optimize the management of the HVAC through the Building Management System. Different working conditions have been simulated, and the numerical output has been used together with experimental data collected from the Company monitoring system. It has been possible to investigate how the extra ventilation required by the new guidelines would affect the total energy consumption and to compare, in terms of energy efficiency, the different HVAC management strategies that could be used to ensure occupants health safety and indoor air quality.
Analysing energy upgrading projects of single-family houses towards a Norwegian nZEB level
Authors: Moschetti R , Time B , Gullbrekken L , Heide V , Georges L , Lien Anne G
Published: December 2021

As the existing building stock is responsible for high energy use and greenhouse gas emissions, energy upgrading projects have been acknowledged as crucial for the energy performance improvement of existing buildings, as well as for environment preservation and rational use of resources. The aim of this article is to investigate the definition of a nearly zero-energy building (nZEB) level for the energy upgrading of single-family houses. In particular, the findings from a research project, i.e., “energy upgrading of wooden dwellings to nearly zero energy level” (OPPTRE), are presented and discussed. A core task of OPPTRE was to carry out an architectural competition, where six interdisciplinary teams proposed innovative solutions for upgrading to a nZEB level representative Norwegian wooden single-family houses, from the period 1950-1990. The upgrading measures proposed in the OPPTRE competition focused on several aspects, such as architectural quality, indoor thermal environment, energy use/generation, carbon footprint, and cost effectiveness. General principles for a nZEB level achievement in upgrading projects are discussed in this article, as deducted from the evaluation of the results of the OPPTRE architectural competition. In particular, the focus is on examining the solutions proposed for upgrading building envelope and technical building systems. Energy use, energy generation, investment costs, and CO2 emissions are examined across the various OPPTRE projects, striving to define a trade-off among different parameters for the achievement of a nZEB level. The findings of this paper support the creation of knowledge in nearly zero-energy upgrading of wooden single-family houses, aiming to a more systematic definition of a nZEB level in such projects. This can be relevant for several stakeholders, such as governmental institutions, homeowners, builders, and private or public decision makers, towards the market uptake of nZEB upgrading by 2030.
Numerical assessment of self-sufficiency of residential buildings in Belgium by using heat pumps, photovoltaic panels and energy storages
Authors: Simic Katarina , Thiers Klaas , Montyne Hugo , Desmet Jan , De Paepe Michel
Published: December 2021

Residential buildings claim a significant share of the total energy use worldwide. In order to have more realistic energy performance predictions, increased attention is paid to the analysis of the building’s energy use through comprehensive, transient detailed numerical simulations. In this article, the self-consumption and self-sufficiency values of three detached residential buildings are assessed through numerical models made in the programming language Modelica and software tool Dymola. The three buildings have the same structure and different space heating energy demands of 15 kWh/m2year, 30 kWh/m2year and 45 kWh/m2year. The energy use of the buildings coincides with the occupancy profile where domestic hot water use dominates over the space heating demand provided by an air to water heat pump. The discrepancy between renewable energy production and energy consumption is mitigated by means of thermal load shifting and electrical energy storage. In this research, the self-consumption and self-sufficiency of the studied buildings have been analysed as a function of the economically favourable energy storage sizing. For the use of an electrical battery with the installed capacity of 2.5 kWh and thermal energy storage of 250 l, the self-sufficiency results to be 40%, 38.5% and 37% for the three buildings respectively at the specific simulated energy demand conditions.
Thermal behavior of light earth used for building insulation: Insight on PCM introduction impact
Authors: Alassaad Farjallah , Touati Karim , Levacher Daniel , Sebaibi Nassim
Published: December 2021

To reduce building significant contribution to greenhouse gas emissions, architects and engineers are seeking eco-friendly construction solutions. Among investigated options, building’s thermal insulation and heat storage can be cited.

In this regard, earth-based materials are attracting particular interest. These last years, there is a renewed interest in these eco-friendly building materials and techniques. This is due to many advantages that they present: excellent humidity regulation ability and high thermal inertia. Present study aims to improve light earth thermal properties. Specifically, this research work focuses on the development of an insulating and heat storing material. To achieve this, phase change materials (PCM) are incorporated in soil-natural fiber mixtures.

In fact, different light earth samples are first prepared. Then, thermally characterized to highlight the impact of PCM on the light earth thermal insulating, heat storing properties and thermal response to changing boundary conditions. The incorporation of PCM showed an interesting improvement of the light earth thermal properties namely on thermal conductivity, specific heat capacity, and thermal comfort time.