bluuebunny/crossref_metadata_2025 huggingface dataset:
Can collected hygrothermal data illustrate observed thermal problems of the façade? – A case study from Greenland
Authors: Friis N K , Møller E B , Lading T
Published: December 2021

Buildings are more vulnerable to faults in design and construction, when exposed to the extreme Greenlandic climate, however, most new materials and designs have not been tested for Arctic conditions. Thus even minor errors can result in failures like mould growth, discomfort, and unnecessary heat loss. Rekognizing the source of the error can be difficult, yet valuable. But how can it be identified whether the error lies in the design or quality of workmanship? This paper describes a case study from Nuuk, Greenland, where a new mineral wool insulation system was implemented. Residents were complaining about draft and cold areas. An investigation revealed that inaccurate use of the system caused several problems. Simulations of the exterior wall performance were conducted and compared to measurements. This paper discusses whether these measurements and simulations support the identified issues, and therefore if this kind of general surveillance of exterior walls can be used to determine the total performance of an exterior wall. The paper concludes that the collected data can support the issues of the complaints, and that the fundamental reasons for the problems are the design, the precision of the casted concrete and the lack of a wind barrier protecting the insulation.
Weather and indoor climate in Greenland
Authors: Møller E B , Helgason J
Published: December 2021

To make a hygrothermal assessment of a building construction, e.g. wall or roof, weather files as well as information on indoor moisture load are needed, however only to some extent available for Greenlandic conditions. This paper describes a project that had a twofold aim: 1) create weather files for four different cities in Greenland in a simple way, 2) determine the typical moisture load in a Greenlandic dwelling to see if the international standard ISO 13788 is applicable in Greenland when describing indoor moisture load. The four chosen cities are placed at the west coast of Greenland. Hourly weather data of 10 years for the four cities were obtained from the meteorological institutes of Denmark and Greenland, from this a reference year with hourly values was created for each city. The paper also describes how incomplete data was treated. Five dwellings were chosen in each city to assess the indoor moisture load. Temperature and relative humidity were measured hourly in living rooms of these dwellings. Furthermore, outdoor temperature and relative humidity were measured in the four cities. The moisture load in the dwellings were scattered in humidity class 1-4, similar to what has been measured in Danish dwellings, consequently ISO 13788 may be applicable in Greenland.
Circularity concepts for offsite prefabricated energy renovation of apartment buildings
Authors: Kuusk Kalle , Kullerkupp Kristel , Pihelo Peep , Ritzen Michiel , Tisov Ana , Kalamees Targo
Published: December 2021

Deep energy renovation includes the realisation of the full potential of energy performance. A circular deep renovation, which contributes to a circular built environment, is based on 100% life cycle renewable energy, and all materials used within the system boundaries are part of infinite technical or biological cycles with the lowest quality loss as possible. In the current study, the circularity potential was assessed for deep energy renovation from different aspects: circularity of materials, building component and building structure. Careful selection of materials as well as connection, position and disassembly possibilities are needed to increase the degree of circularity. This shows a good possibility to increase energy performance by using circularity principles. The window glass circularity analyse showed that, at best, the thermal transmittance of a new circular product can be more than three times lower than the original. The circular use of materials, components, and structures pose new challenges for the building physic design of building envelope structures.
A preliminary scenario analysis of the impacts of teleworking on energy consumption and greenhouse gas (GHG) emissions
Authors: Kharvari Farzam , Azimi Sara , O’Brien William
Published: December 2021

This paper uses scenario analysis to investigate the broader impact of teleworking in four scenarios including the COVID-19 pandemic, worst-, moderate-, and best-case scenarios on building-level energy use, energy consumption in transportation, and information and communication technology (ICT) usage by using the databases of the Government of Canada. The COVID-19 scenario relies on the available data for the pandemic period. The worst-case scenario is when telework has an adverse effect on energy use while the moderate-and best-case scenarios are when the minimum and maximum savings are achieved by telework. The data includes commuting distances, electricity and natural gas consumption for offices and residential buildings, and ICT usage. Then, the associated GHG emissions are calculated for transportation, residential and office buildings, and ICT and the analysis are carried out by applying a potential fraction of saving to the associated GHG emissions of each domain and scenario. This paper demonstrates the potential energy savings of teleworking significantly depends on teleworker behavior to a degree that in the worst-case scenario no potential saving is observed while the savings are significant in the best-case scenario. Therefore, the impact of telework is highly uncertain and complicated and current statistics are insufficient for accurate estimates.
Hygrothermal assessment of internally insulated historic solid masonry walls with focus on the thermal bridge due to internal partition walls
Authors: Jensen N F , Rode C , Møller E B
Published: December 2021

This study investigated the hygrothermal performance of five insulation systems for internal retrofitting purposes. Focus was on the hygrothermal performance near partition brick walls compared to the middle of the wall. The setup comprised two insulated reefer containers with controlled indoor climate, reconfigured with several holes containing solid masonry walls with interior embedded wooden elements, an internal brick partition wall and different internal insulation systems, with and without exterior hydrophobisation. Relative humidity and temperature were measured over five years in the masonry/insulation interface and near the interior surface, in the centre of the test field and near the partition wall. In addition, calibrated numerical simulations were performed for further investigation of the thermal bridge effect. Findings for the masonry/insulation interface showed higher temperatures and lower relative humidity near the partition wall in comparison with the central part of the wall. Near the interior surface, measurements showed only minor differences between the two locations. The relative effect of the thermal bridge was smaller in the case of a high driving rain load on the exterior surfaces. The numerical simulations showed that the hygrothermal conditions were affected further away from the partition wall than what could be measured in the experimental setup.
Active Environmental Control Strategies for Brick Historical Buildings, Combining Heritage Conservation and Thermal Comfort
Authors: Cai YK , Xie H R , Ma Y , Hokoi S , Li Y H
Published: December 2021

For historical buildings, it is a challenge to utilize HVAC system to improve the thermal comfort within a reasonable range without increasing the risk of deterioration. This research selected a traditional temple building located in Hubei Province, China, aiming to clarify the impact of different operation modes of heating systems on the preservation status of the building, and to further propose reasonable active environmental control strategies. A two-dimensional hygrothermal model of the temple building was established and used to evaluate the influence of different heating parameters, operation schedules, and ventilation strategies on heritage conservation and thermal comfort with the application of floor heating. The main conclusions are as follows: for Honghua Temple, low-level heating at 16 °C with conventional ventilation or heating at 18°C with enhanced ventilation is the preferred solution; enhanced ventilation mode can reduce the risk of mold growth while satisfying the convenience of using the Buddha worship space; for intermittent heating in winter, preheating the system is necessary, and maintaining a low heating level at night is more conducive compared with shutting down the system directly; the impact of evaporation increasing caused by heating should be weighed in active environmental control.
Assessment of Deterioration Risk of Maijishan Grotto under the Radiation Difference Based on Heat and Moisture Transfer Model
Authors: Wu R B , Ma Y , Xie H R , Hokoi S , Yue Y Q , Li Y H
Published: December 2021

The ambient environment of architectural heritage is an important factor affecting its conservation. Two adjacent rows of Buddha statues in Grottoes No. 3 (semi-open) of Maijishan Grotto in Gansu, China, show apparent differences in the degree of deterioration. This study made a monitoring scheme of grottoes microenvironments such as air temperature, relative humidity, radiation, and surface temperature to explore the cause of the difference. A two-dimensional heat and moisture (HAM) transfer model was established and verified to simulate the temperature and humidity on the surface and inside of the Buddha statues. Then, temperature and water content fluctuation and the risks of thermal stress destruction on the surface and near the surface of the Buddha statues were evaluated. The results show that the radiation difference causes thermal stress and water content differences both in heights and in depths. This impact brought by the direct sunlight may contribute to the different deterioration on the two rows of Buddha statues. The eaves shaded the upper row of the Buddha statues much longer than the lower ones. Less severe fluctuation and differences in temperature and water content occur at the middle and upper points. This study evaluates the degradation of Grottoes No. 3 and has guiding significance for its preservation methods.
Hygrothermal Evaluation of Waterline Rising of a Masonry Tower based on Measurements and Simulations
Authors: Xie Q H , Li Y H , Ma Y , Hokoi S , Xie H R
Published: December 2021

Wet walls in ancient masonry buildings are common due to rainfall, groundwater and other environmental factors, and usually accompanied by the degradation phenomena such as powdering, shedding, salting out, which threatens the value and safety of ancient buildings. It is found that the bottom of Dayan Pagoda has been damp and gloomy for a long time. In recent 40 years, the waterline at the bottom has risen by about 0.5 ∼1m, and the wet area on the north wall is as high as 5m. This paper aims to clarify the cause of the rising waterline and the water source of Dayan Pagoda. The correlation between degradation of Dayan pagoda and environmental factors such as temperature, rainfall and solar radiation was established. Firstly, there was a field measurement on the waterline height in different orientations of Dayan Tower; Then, a coupled heat and moisture transfer model was developed to obtain the hygrothermal distribution in the brick wall, and the impact of rainfall and groundwater was evaluated, and the rising trend of waterline in the future was predicted. The field measured results show that during 2018-2020, the waterline of the west wall of Dayan Pagoda has the largest rise (about 20cm), while the south wall has the smallest rise (about 10cm). The simulation results show that the water source of rising waterline is mainly wind-driven rain rather than groundwater rising. The result contributes to propose environmental control measures to alleviate the degradation of masonry buildings caused by water.
Internal Insulation of Preservation Worthy Facades
Authors: Lucchesi  , Svendsen  , Koldtoft
Published: December 2021

With international awareness of the need to decrease greenhouse gas emissions, the Danish government set a target to be fossil fuel-free by 2050. To achieve that, existing buildings will need to be retrofitted with energy-saving technologies such as improved thermal insulation. In Denmark, a larger mass of the building stock from around 1850 to the 1940s is preservation worthy. The construction is typically solid brick walls with wooden beams on the floors. This creates a challenge for energy retrofitting since the external facades cannot be altered. The application of internal insulation can influence the temperature and moisture profile of the wall. Moisture builds up in the interface between the original brick wall, and the insulation layer can create an environment where mould can grow. Previous research also demonstrated a risk of moisture build-up at the beam-ends when internal insulation is applied. Saint-Gobain ISOVER has, together with DTU, spent five years developing a new system, ISOVER RetroWall System, which addresses these problems. The presented work will include a short introduction to the concept, results and conclusions from the field test and presentation of two sites with the finished system in use.
Desalination using clay and lime sacrificial plasters with additives on field stone wall and fired clay bricks
Authors: Leiten K , Sirelpuu H , Kiviste M
Published: December 2021

Salt deteriorations can ruin the appearance as well as the structure of buildings. Salt deteriorations can be mitigated by passive and active methods. Common active methods include sprinkling water on the structure, scraping off the concentrated salts from the surface and the use of sacrificial plasters. Sacrificial plasters are traditionally used for desalination. Two tests at different sites were performed in order to determine the effectiveness of desalination of different sacrificial plasters. The first test site was a two hundred years old stable wall in Mooste county, Estonia. Salt percentage by mass in the test wall was determined in 2017 and again in 2019. In December 2019 different plasters of local natural clay and lime with additives such as hemp flax, charcoal and turf were tested on the wall. The second test was performed on burnt clay bricks that were placed into salt solution until efflorescence appeared. For desalination process again, different clay and lime based sacrificial plasters were used. After removing the sacrificial plaster, samples from the mortar and bricks were taken to measure the salt content by using Ion chromatography. Clay and hemp flax based sacrificial plasters were the most suitable for desalination and removal.
Thermal Conductivity and Specific Heat Capacity of Insulation materials at Different Mean Temperatures
Authors: Yousefi Y , Tariku F
Published: December 2021

Thermal conductivity and heat capacity are among the most essential properties of a building insulation in calculating thermal performance which are subjected to change when exposed to temperatures variation in service. Ignoring the temperature dependency of these material properties can result in under and over estimations of buildings energy uses and the corresponding equipment sizing. To obtain more realistic conductivity values of insulation materials, in this paper, thermal conductivity tests are conducted at various mean temperatures. For the study six commonly used insulations including Cellulose fiber, Expanded Polystyrene, Extruded Polystyrene, Open Cell Spray Polyurethane, Polyisocyanurate, and Mineral Wool are considered, and their thermal conductivity are measured at seven mean temperatures ranging from 5°C to 60°C. Furthermore, their specific heat capacity are measured at nine mean temperatures ranging between 16°C and 36°C. The results showed that except Polyisocyanurate board, the thermal conductivities and specific heat capacities of all insulation materials increased linearly with rising temperature, presenting a linear regression model with correlation coefficients (R2) values between 0.96 and 0.98. The curve fitting of the Polyisocyanurate thermal conductivity measurements resulted a nonlinear regression model with R2 of 0.97. The thermal conductivity of six insulations as a function of temperature have been established.
Evaluation of the intrinsic thermal performance of an envelope in the summer period
Authors: Jay A , Fares H , Rabouille M , Oberle P , Thebault S , Challansonnex A , Anger J
Published: December 2021

Ensuring the proper thermal performance of a building’s envelope upon reception is an important stage in the life cycle of the building. Several methods already exist for this purpose, and continue to be improved, such as co-heating, ISABELE, EPILOG, QUB and SEREINE. All these methods follow the common protocol consisting of heating the measured building. These measurement protocols quantify the dynamic evolution of interior and outdoor temperatures, and the thermal power injected into the building and these data are used in calibration algorithms to determine, by an inverse method to deduce a heat loss value. These methods require a difference of a few degrees between the interior and the exterior which can cause in summer periods a risk of damaging the building, as the outside temperature may already be high.

The objective of this work is to explore the possibility of determining the intrinsic thermal performance of a building’s envelope in the summer period using a cooling system. This work leans on an experiment of a square meter scale cell and explore the capacities and limitations of the method at this scale by varying several stress parameters of the enclosure. Results in cooling mode are also compared to heating mode.
CFD investigation of natural ventilation in a family house in Hungary
Authors: Ali Modar , Katona Ádám László , Kistelegdi István
Published: December 2021

Buildings are responsible for around 40% of greenhouse emissions globally. The residential building sector is responsible for 24% of energy use. In Hungary, about 800.000 ‘Cube houses’ which date back to the socialist era are still standing. These houses suffer shortages from the energy point of view. This paper presents a new refurbishment approach that attempts to achieve passive cooling with aerodynamic design by integrating the “Venturi disc” which stimulates natural ventilation and night cooling. The work was achieved by using Computational Fluid Dynamics (CFD) simulations using ANSYS Fluent software tool. The implemented building provides lower energy demand and considerably higher comfort in comparison with the typical ‘Cube house’. The building is not only a case study, rather a sustainable model for all the ‘Cube houses’ renewal and further family housing renovations or constructions to reach a higher standard. This paper is a step in an ongoing research project.
On-site measurement and numerical investigation of thermal environment with different air distribution systems in ice arenas
Authors: Lin Wenyu , Zhang Tao , Liu Xiaohua , Li Lingshan
Published: December 2021

It is important to strictly maintain the indoor thermal environment in ice arenas which have very different features to other commercial buildings. Separated air distribution system is widely used to create a dry and cold environment near the ice and a comfortable environment in the view stand. The warm and humid air from the view stand may lead to uneven temperature and humidity distribution in the rink, leading to extra energy consumption, even fog and frost on the ice. Unreasonable air supply in the ice rink zone will also make the spectators feel too cold and uncomfortable. Jet ventilation system is the most extensively used system in the ice rink zone. An innovative ground displacement ventilation system is proposed in the National Aquatics Centre, which will serve as the venue for the curling competition in the 2022 Beijing Winter Olympics. On-site measurement in the arena is carried out and computational fluid dynamics (CFD) simulation method is adopted in the present research. Measured thermal environment above the ice with different ventilation systems are compared and analysed. Result shows that the displacement ventilation system features a more obvious vertical stratification than jet ventilation system in this kind of large space buildings, and thus is more energy-efficient. A CFD model of the ice cube is setup and verified by measured data. The thermal environment in the ice rink with displacement ventilation under extreme condition is studied using the simulation method. The temperature and humidity in the ice field increases by 10.1 °C, 4.5 g/kg without air supply in the view stand, proving that the spectators in the view stand have a great impact on the thermal environment in the ice field.
A simplified model for calculating heat transfer through the double skin facade
Authors: He G , Meng Y , Zhu J , Zhang S
Published: December 2021

Double skin façade (DSF) has been recognized as a flexible type of envelope that can adapt to various building needs, such as insulation, solar heat gain, ventilation, and shading. This adaption ability makes the DSF a potentially high performance envelope. However, the reliable calculation of the heat flow in the DSF has been a challenging task due to the complex heat transfer process involved in the DSF. In this study, we propose a simple model that aims to simplify the heat transfer calculation involved in the DSF. In this model, a characteristic function of heat transfer coefficient (CFHTC) was proposed for the heat transfer between the inner layer and the outside air, which would otherwise call the complex convective heat transfer in the cavity. We use experimental data to demonstrate that this function can be expressed as a function of the incident solar intensity. This CFHTC is supposed to be dependent on the geometry of the DSF. With the CFHTC, the calculation of the heat transfer between the inner layer of the DSF and the outside air is simplified and can be incorporated in energy simulation tools.
Evaluation and use of airspaces for thermal resistance in buildings
Authors: Saber H H , Yarbrough D W
Published: December 2021

The thermal resistance (R-value) of airspaces depends on the emittance of surfaces around the airspace, dimensions, heat-flow direction, and the temperatures of bounding surfaces. Assessing the energy performance of building envelope components and fenestration systems requires accurate results for the R-values of any enclosed spaces. The evaluation of reflective insulation R-values has evolved to include use of computational fluid dynamics and surface-to-surface radiation to quantify convective and radiation contributions to the heat transfer across airspaces of all types. This paper compares an advanced and validated computational tool for calculating enclosed airspace R-values with the widely-used ISO 6946 and airspace R-values in the ASHRAE Handbook-Fundamentals. The tool evaluates construction defects, air-infiltration impact, and dimensional aspect ratios that 1-D methods do not address. The differences between the methods that are currently being used to evaluate the R-value and the advantages of the advanced method for evaluation of reflective insulation applications are discussed.
Validation of radiant and convective heat transfer models of photonic membrane using non-invasive imaging of condensation pattern
Authors: Teitelbaum E , Aviv D , Hou M , Li J , Rysanek A , Meggers F
Published: December 2021

Cooling a sample of a material until condensation is observed is a standard technique for accurately measuring the dewpoint and associated relative humidity in a volume. When conducting an experiment with a membrane-assisted radiant cooling panel, we found that membrane surface temperatures were difficult to measure directly. Instead, the onset of condensation was used to infer the membrane’s surface temperature. However, the radiant cooling panels displayed variations of membrane surface temperature at steady state, and thus a resulting condensation contour was observed, forming a curve on which the membrane surface temperature was accurately known and constant - the dewpoint. The curve was in equilibrium between the internal panel temperature driven by internal free convection in the air gap and the view factor to surrounding surfaces, which can be evaluated at each point along the curve. In this paper, we assess the convective and radiative heat transfer balances using simulations. Our methods expand the “sensing” of condensation to provide information about view factor and thermal stratification, both of which are quantities that are difficult to measure adequately in the field.
Investigating the relationship between residential AC, indoor temperature and relative humidity in Indian dwellings
Authors: Gupta Rajat , Antony Anu , Garg Vishal , Mathur Jyotirmay
Published: December 2021

Residential electricity consumption (REC) in India has tripled in the past two decades accounting for 24% of the overall electricity consumption during 2018-19. Residential air conditioning (AC) usage is responsible for about 20%-40% of REC in India. This paper investigates the relationship of residential AC use with indoor temperature and relative humidity (RH) using concurrent time-series monitoring data gathered in eight dwellings during summer and monsoon seasons. Contextual data about the dwelling (physical) and household characteristics were gathered using face-to-face interview based surveys. The dwellings were located in Hyderabad representing the composite climate of India. The mean daily electricity consumption was found to be higher in summer (11.5kWh) possibly due to the higher usage of AC (because of higher ambient conditions) as compared to 6.5kWh/day during monsoon season. Binary logistic regression identified the trigger indoor temperature and RH at which AC was likely to be switched on in the summer as 29 °C - 31.9 °C for indoor temperature and 36%-38.9% RH. In the monsoon season AC was predicted to come on sooner at 26°C-28.9°C but at higher RH range of 59%-61.9%. These empirical findings can be used to reduce residential cooling energy demand through smart management of ACs in Indian dwellings.
Primary energy efficiency assessment of a coil heat recovery system within the air handling unit of an operating room
Authors: Rey-Martínez F J , San José-Alonso J F , Velasco-Gómez E , Tejero-González A , Esquivias P M
Published: December 2021

Heat recovery systems installed in Air Handling Units (AHUs) are energy efficient solutions during disparate outdoor-to-indoor temperatures. However, they may be detrimental in terms of a primary energy balance when these temperatures get closer, due to the decrease in the thermal energy recovered compared to the global energy consumption required for their operation. AHUs in surgical areas have certain particularities such as their continuous operation throughout the year, the large airflows supplied and the strict exigencies on the supply air quality, avoiding any cross contamination. This work presents the measurements and analysis performed on a coil heat recovery (run-around) loop system installed in the AHU that serves a mixed-air ventilation operating room in a Hospital Complex. A primary energy balance is studied, including the thermal and electric energy savings achieved, considering the electric energy consumption by the recirculation pump and the additional power requirements of fans due to the pressure drop introduced. The obtained value is then used to predict the thermal energy savings achieved by the heat recovery system. Results are extrapolated to the Typical Meteorological Year to provide an order of magnitude of the primary energy and CO2 emissions saved through the operation of the coil heat recovery system.
A bi-directional approach to building-integrated PV systems configuration
Authors: Mahdavi A , Wolosiuk D , Berger C
Published: December 2021

The configuration of local building-integrated photovoltaic (PV) installations can benefit from computational support. Especially in cases where a high degree of energy self-sufficiency is desired, it is important to optimally match the temporal profiles of the building’s energy demand and the available solar radiation intensity. Typically, the building’s demand profile is taken as given, which is treated as the basis for the sizing and configuration of the PV installation. The computational approach framework introduced in this paper is intended to offer additional functionalities. Specifically, it is conceived to facilitate a bi-directional approach to supporting the design and configuration of PV installations. This approach not only informs the configuration of PV system based on the building’s demand profile, but also allows for the exploration of the consequences of the magnitude and temporal profile of the PV’s energy supply potential for the values of relevant building design variables (e.g., building orientation, fraction of glazing in the envelope). The paper presents this computational approach and its functionality in terms of an illustrative case study.
Thermal performance of ETICS, energy activated with PCM and PV
Authors: Talvik Martin , Ilomets Simo , Kalamees Targo , Klõšeiko Paul , Heim Dariusz , Wieprzkowicz Anna , Knera Dominika
Published: December 2021

Installing photo-voltaic (PV) panels on building façades is a growing tendency that helps to achieve both newly built and renovated nearly zero energy buildings. A novel approach to building active facades is to use a phase change material (PCM) behind the flexible PV. The PCM stabilises the PV’s temperature which can lead to an increase in energy production and cuts down the temperature peaks to avoid damage. In this study, the thermal performance of an En-ActivETICS wall was modelled in three different locations across Europe. The model was validated against on-site temperature measurements. The efficiency of the PV was calculated and an optimal PCM thickness and melting temperature were selected. The results show that annual energy production of the PV panel could increase between 2% (in Lodz) to 5% (in Madrid) using a 40mm-thick PCM. The optimal PCM melting temperatures for a certain climate should be chosen as 0 to 10 degrees below maximum air temperature in summer. The maximum peak PV temperatures could be reduced by ca. 20 K (from ∼90 to ∼70°C). Reasonable way to fix the stainless steel casing to the wall would be with four stainless steel anchor bolts – that gives 78% or 93% efficiency in case of EPS or PIR thermal insulation, respectively.
Impact of Phase Change Material (PCM) glazing on the energy consumption and solar radiation transmission in an office room located in a semi-arid climate: Analysis of a real-scale experiment
Authors: Uribe Daniel , Vera Sergio
Published: December 2021

Phase Change Materials (PCMs) are materials with high latent heat. When integrated into the glazing, they arise as an innovative strategy to improve thermal performance and provide thermal inertia in office buildings with a lack of opaque. Climates with high solar radiation and great temperature variation between day and night are especially interesting because PCM glazing can vastly improve these buildings’ energy performance. Then, this paper aims to analyze the energy performance of an office room with PCM glazing compared to a reference room with double-clear glazing, in a semi-arid climate. A real-scale experiment was carried out for a year in two office rooms located in Santiago, Chile. The analyses include energy consumption of the HVAC system to keep the interior temperature of the room in the comfort range and the solar radiation transmitted through the windows. Results are presented for three representative weeks of summer, mid-season and winter. An important reduction of the solar radiation transmitted was achieved in the PCM glazing in respect to the double-clear glazing when the phase change occurs, and a decrease of the energy consumption of cooling and heating mainly for sunny and variable days was found.
Preliminary Experimental Assessment of Building Envelope Integrated Ventilative Cooling design
Authors: Girma G , Tariku F
Published: December 2021

To minimize energy consumption, high-performance buildings are being built with highly insulated and airtight building envelopes, high-performance glazing and efficient mechanical systems. But it has been observed that these buildings are prone to an overheating problem during the summertime. Literature suggests a ventilative cooling method, which is the use of natural ventilation for space cooling, as an ideal system for energy saving and overheating prevention. In this study, the behaviour of a building envelope integrated ventilative cooling (EV wall) design is experimentally studied to assess its cooling potential and ventilation capacity. The EV wall design has an opening at the bottom of the wall that allows ventilative air exchange between the indoor and the outdoor through the cavity behind the cladding. The suction pressure created by the buoyancy effect in the wall cavity drives the ventilation air. The experimental assessment has shown that there are two distinct night-time and day-time flows driven by indoor/outdoor temperature difference and solar radiation respectively. This preliminary study indicated the huge potential of ventilative cooling design and ways to further enhance the EV wall performance. For future studies, the EV wall will be considered by implementing an opening control system in a naturally ventilated building.
Utilizing a novel mobile diagnostics lab to validate the impact of vegetative wall coverings in building cooling load reduction
Authors: Fagbule O , Patel R , Passe U , Thompson J
Published: December 2021

Building cooling loads are driven by heat gains through enclosures. This research identifies possible ways of reducing the building cooling loads through vegetative shading. Vegetative shading reduces heat gains by blocking radiation and by evaporative air cooling. Few measured data exist, so we gathered thermal data from a vegetative wall grown in front of a Mobile Diagnostics Lab (MDL), a trailer with one conditioned room with instrumentation that collects thermal data from heat flux sensors and thermistors within its walls. In spring 2020 a variety of plants were cultivated in a greenhouse and planted in front of the south façade of the MDL, which was placed in direct sunlight to collect heat flux data. The plants acted as a barrier for solar radiation and reduced the amount of thermal energy affecting the trailer surface. Data were collected through the use of 16 heat flux sensors and development of continuous infrared (IR) images indicating surface temperature with and without plant cover. The façade surface beneath the plants was 10-30 °C cooler than exposed façade areas. In further analyses, the heat-flux data were compared to IR temperature data.
Electrochromic Glass system in Norwegian Climate: Control strategies and Impact on the indoor thermal conditions
Authors: Nocente A , Grynning S , Gullbrekken L
Published: December 2021

This work investigates by simulations the impact of the use of Electrochromic (EC) windows in a modern wooden cabin with large window area in a colder climate. The climatic areas considered are 4 different locations in Norway. Three different automatic control systems were used and compared. The windows were alternatively equipped with a textile integrated external blind and an EC glass. The results show that the use of EC glass has a quantifiable impact in term of reduction of peak temperature by 2°C and reduction of number of hours with high indoor temperature. The control system that seems to perform better is based on external solar radiation. In the particular situation of a cabin, where the visual comfort and the surrounding view has the greatest importance, a more complex control algorithm needs to be developed.
Parametric Energy Simulation Methods for Solar-NIR Selective Glazing Systems
Authors: Duan Qiuhua , Zhang Enhe , Hinkle Laura , Wang Julian
Published: December 2021

Solar near-infrared (NIR) selective glazing systems have been proposed by incorporating photothermal effects (PTE) of a nanoparticle film into building windows. From an energy efficiency perspective, the nanoscale PTE forms unique inward-flowing heat by heating up the window interior surface temperature under solar near-infrared, significantly improving the window thermal performance. Also, the PTE-driven solar heat gains are dynamic upon solar radiation and weather conditions. However, the PTE on annual building energy use has not been investigated thoroughly, due to the lack of an accurate and appropriate energy simulation method. In this study, we used the EnergyPlus energy management system to develop a parametric energy model and simulation approach in which a solar-temperature-dependent thermal model was embedded into the parametric energy simulation workflow. Applying this method, we examined the solar near-infrared-dependent PTE-induced thermal performances of glazing systems and their effects on annual heating energy use in representative cold climates (i.e., Zones 4, 5, and 6). The results show that the dynamic model considering the PTE demonstrated more heating energy savings, up to 11.64% in cold climates, as opposed to the baseline model that ignored the PTE. This work presents a method to model and simulate the dynamic thermal performance of windows with PTE.
In situ U
g-value measurement on three different glazing types
Authors: Paschke F , Bishara N , Schulz I , Kocer C , Schneider J , Maier A
Published: December 2021

This study presents in situ monitoring data of three different glazing systems over a period of one year. An insulated glass unit (IGU), a Vacuum Insulated Glass hybrid unit (VIG-hybrid) and an opaque architectural insulation module (AIM) were monitored under the equivalent environmental condition in this study. Different issues were observed and analyzed. It was found that the Ug-value cited by the manufacturers agrees with the Ug-values derived from the measured data, to within less than 5 % for the IGU and the VIG-hybrid. The consistency of the Ug-value of each glazing types one year after the start of monitoring was validated for similar environmental conditions. Depending on the magnitude of the resistance to heat flow, an increasing Ug-value was observed for a higher temperature difference between the inside and outside environments. The effect is much more significant for the glazing type with the largest Ug-value (IGU) and less significant for the glazing types with a high thermal resistance (VIG-hybrid, AIM).
Simulating heat load profiles in buildings using mixed effects models
Authors: Palmer Real J , Kloppenborg Møller J , Rasmussen C , Lindberg K B , Sartori I , Madsen H
Published: December 2021

The landscape of buildings is a diverse one and long-term energy system planning requires simulation tools that can capture such diversity. This work proposes a model for simulating the space-heating consumption of buildings using a linear mixed-effects model. This modelling framework captures the noise caused by the differences that are not being measured between individual buildings; e.g. the preferences of their occupants. The proposed model uses outdoor temperature and space-heating consumption measured at hourly resolution; thus, the model is able to predict the intra-day variations as well as longer effects. Given the stochastic nature of the simulation, the prediction interval of the simulation can be estimated, which defines a region where the consumption of any unobserved building will fall in. A whole year has been simulated and compared to out-of-sample measurements from the same period. The results show that the out-of-sample data is virtually always inside the estimated 90% prediction interval. This work uses data from Norwegian schools, although the model is general and can be built for other building categories. This amount of detail allows energy planners to draw a varied and realistic map of the future energy needs for a given location.
A review on coupled building physics analyses
Authors: Bühler M. , Bednar T.
Published: December 2021

This paper reviews methods and tools for coupled building physics analyses in the context of Building Performance Simulations (BPS) with a focus on Building Energy Simulations (BES) and Computational Fluid Dynamics (CFD) as a common application. Furthermore, requirements regarding the necessary information for simulations, data models and coupling are identified. Possibilities of automated simulation model generation, data exchange and the performance of existing multi physics simulation models are analysed and limiting factors are discussed.
Anomaly detection and missing data imputation in building energy data for automated data pre-processing
Authors: Takahashi K , Ooka R , Ikeda S
Published: December 2021

A new trend in building automation is the implementation of smart energy management systems to measure and control building systems without a need for decision-making by human operators. Artificial intelligence can optimize these systems by predicting future demand to make informed decisions about how to efficiently operate individual equipment. These machine learning algorithms use historical data to learn demand trends and require high quality datasets in order to make accurate predictions. But because of issues with data transmission or sensor errors, real world datasets often contain outliers or have data missing. In most research settings, these values can be simply omitted, but in practice, anomalies compromise the automation system’s prediction accuracy, rendering it unable to maximize energy savings. This study explores different machine learning algorithms for anomaly detection for automatically pre-processing incoming data using a case study on an actual electrical demand in a hospital building in Japan, namely cluster-based techniques such as k-means clustering and neural network-based approaches such as the autoencoder. Once anomalies were identified, the missing data was filled with prediction values from a deep neural network model. The newly composed data was then evaluated based on detection accuracy, prediction accuracy and training time. The proposed method of processing anomaly values allows the prediction model to process collected data without interruption, and shows similar predictive accuracy as manually processing the data. These predictions allow energy systems to optimize HVAC equipment control, increasing energy savings and reducing peak building loads.
Study of power demand forecasting of a hospital by ensemble machine learning
Authors: Nakai Mayuka , Ooka Ryozo , Ikeda Shintaro
Published: December 2021

To save energy in existing buildings, power demand can be predicted so a more efficient operation of equipment can be realized, like utilizing heat storage to lower the peak. Many attempts to predict building power consumption by machine learning have used simulation values in virtual buildings with no measurement errors or defects in the data. These models tend to have higher accuracy scores but have the risk of overfitting and possibly malfunction for missing data or outliers. To avoid the problems, this study proposes an ensemble machine learning algorithm to forecast power demand for a hospital building in Japan. Using the power consumption data, predictions were made by using algorithms such as Deep Neural Network (DNN) and Random Forest (RF). Each algorithm was combined to create ensemble models that take the weighted average of the predicted values. Consequently, we overcame the issues of each individual method, and achieved higher prediction accuracies. We selected the appropriate method for forecasting the power demand of real buildings based on accuracy. In future studies, we will apply the same methodology to predict cooling load.
Empowering energy flexibility and climate resilience using collective intelligence based demand side management (CI-DSM)
Authors: Nik Vahid M. , Moazami Amin
Published: December 2021

This work investigates the effectiveness of Collective intelligence (CI) in demand side management (DSM) in urban areas to cope with extreme climate events. CI is a form of distributed intelligence that emerges in collaborative problem solving and decision making. It is used in a simulation platform to control the energy performance of buildings in an urban area in Stockholm, through developing CI-DSM and setting certain adaptation measures, including phase shifting in HVAC systems and building appliances. CI-DSM is developed based on a simple communication strategy among buildings, using forward (1) and backward (0) signals, corresponding to applying and disapplying the adaptation measures. The performance of CI-DSM is simulated for three climate scenarios representing typical, extreme cold and extreme warm years in Stockholm. According to the results, CI-DSM increases the autonomy and agility of the system in responding to climate shocks without the need for computationally extensive central decision making systems. CI-DSM helps to gradually and effectively decrease the energy demand and absorb the shock during extreme climate events.
Low-cost smart solutions for daylight and electric lighting integration in historical buildings
Authors: Scorpio Michelangelo , Ciampi Giovanni , Gentile Niko , Sibilio Sergio
Published: December 2021

Research have shown that the correct integration of daylight and electric lighting reduces the energy use in buildings, while improving visual comfort. Smart shading systems, especially those electrically controlled, play an important role to control solar radiation. Similarly, smart and dimmable/tunable lighting can help to adjust the artificial light to the real users’ needs. This paper presents preliminary results of an ongoing living lab study investigating how artificial lighting systems can be integrated with shading systems, placing human comfort at the heart of the study and yet saving energy. A manually controlled, commercial and low-cost smart system integrating two motorized shading devices and six dimmable LED luminaires with a different selection of CCT were installed in a private office in a historical building. Indoor and outdoor lighting conditions and energy consumption associated to the lighting system are constantly monitored to assess how the people use shading and lighting upon varying the boundary conditions.. Preliminary results highlight that users prefer to maximise daylight on the work plane as well as they generally use both shading and electric lighting systems in response to boundary conditions that cause serious discomfort.
Effect of competitive acoustic environments on speech intelligibility
Authors: Puglisi G E , Warzybok A , Astolfi A , Kollmeier B
Published: December 2021

Excessive noise and reverberation times degrade listening abilities in everyday life environments. This is particularly true for school settings. Most classrooms in Italy are settled in historical buildings that generate competitive acoustic environments. So far, few studies investigated the effect of real acoustics on speech intelligibility and on the spatial release from masking, focusing more on laboratory conditions. Also, the effect of noise on speech intelligibility was widely investigated considering its energetic rather than its informational content. Therefore, a study involving normal hearing adults was performed presenting listening tests via headphone and considering the competitive real acoustics of two primary-school classrooms with reverberation time of 0.4 s and 3.1 s, respectively. The main objective was the investigation of the effect of reverberation and noise on the spatial release from masking to help the design of learning environments. Binaural room impulse responses were acquired, with noise sources at different azimuths from the listener’s head. The spatial release from masking was significantly affected by noise type and reverberation. Longer reverberation times brought to worst speech intelligibility, with speech recognition thresholds higher by 6 dB on average. Noise with an informational content was detrimental by 7 dB with respect to an energetic noise.