Indoor Climate In Buildings Research Articles

Analytical Confirmation of the Calculated Dependencies for Heat Exchange in a Plate Recuperator when Humidifying the Auxiliary Flow

The relevance of the study is related to the need to ensure maximum reduction of energy consumption while ensuring the calculated parameters of the indoor climate in buildings under the Law of the Russian Federation “On Energy Saving...” and the updated version of SP 131. The purpose of the study is to obtain an approximate analytical expression of this dependence, which makes it possible to additionally confirm the results of field and numerical experiments previously performed by the authors for this flow treatment scheme. The objective of the study is to build a simplified mathematical model of the processes of changing the heat and humidity state of the air in the recuperator, identify the main factors affecting the increasing multiplier to the coefficient of temperature efficiency of the device and obtain the necessary numerical coefficients in formulas linking the desired and initial parameters. The general equation of thermal balance and heat transfer for the heat exchanger as a whole is used, including the integral characteristics of the apparatus in a dimensionless form, as well as standard techniques of algebraic transformations. An approximate analytical expression is obtained for an increasing multiplier to the coefficient of thermal efficiency of the recuperator taking into account the additional cooling of the inflow due to the heat consumption for evaporation. It is shown that the general structure of this ratio coincides with the one found by the authors earlier by processing the results of numerical modeling of a two-dimensional temperature field in a heat exchanger, taking into account experimental data on the amount of moisture carried away, which confirms their correctness and reliability.

Preliminary developments and insights of the Smart Building Hub: A Norwegian e-infrastructure for energy-flexible and healthy buildings

Experience from acquiring, processing, and storing data in past and ongoing research projects has proven to be much more time-consuming than expected due to a plethora of data structures, missing metadata, and security issues. Currently, there is no infrastructure in Norway giving researchers access to insight into the energy performance and indoor climate in buildings on a larger scale. Therefore, this article presents the preliminary developments and insights of the Smart Building Hub (SBHub) e-infrastructure, such as the data sources, architecture, relevant stakeholders, use cases, and findings from interviews with identified stakeholders. The lasting contribution of this article aims to fill a critical gap in current research infrastructures in Norway but also sets a precedent for similar initiatives globally, showcasing how interdisciplinary approaches and stakeholder engagement can lead to significant advancements in smart building research.

The impact of glass properties on the energy efficiency and embodied carbon of multi-angled façade systems

This research paper analyses the potential of multi-angled façade systems to achieve the sustainability goals of reduced energy consumption and improved indoor climate quality, hence aligning with UN SDGs 3, 11, 12 and 13. The objective of this research paper is to define the suitable glass properties for the two windows of the multi-angled façade. The concept of a multi-angled façade system is based on proposing using two different window orientations in each façade on a vertical axis (right and left), but not tilted up and down. The large part of the multi-angled façade is oriented more to the north to optimise the use of daylight and the small part of the multi-angled façade more to the south to optimise the use of solar radiation through the façades. One can optimise using daylight and solar heat inside the office room through the multi-angled façade design concept, but with less complexity in the design, manufacture, and transport phases. This is the gap between 3D façades and the new multi-angled façade system concept, which indicates its novelty.To evaluate the energy consumption, the researcher used the software program IDA ICE version 4.8. to analyse the energy behaviour through the façade and the building's indoor climate, to compare the glass property impacts. The researcher modelled five scenarios for a multi-angled façade with different glass properties in both parts of the multi-angled façade. Researchers have used this software in simulations to validate, test, and compare statistics for more than 25 years according to ASHRAE 140, 2004, and CEN Standard EN 15255 and 15265, 2007. To conduct the analysis for the material's embodied energy in the multi-angled façade, the researcher used the software LCAbyg version 5 and compared it with the situation for a flat façade. The results for the energy consumption results revealed that the energy behaviour in the first scenario's glass type is recommended because the illumination was better and offered lower total yearly energy consumption and the accepted number of overheating hours inside the office room. The result of the embodied energy for the materials of the multi-angled façade shows that the area-weighting of the sum of the total energy consumption through the building's lifetime and embodied energy is higher when one renovates with a flat façade by about 11%.

Study of Natural Ventilation Strategies in the São Cristóvão Church in Lisbon Using a Multizone Airflow Model

Visitors have a significant impact on the indoor climate of buildings housing works of art, and the relationship between the number of visitors, the indoor air quality and the protection of exposed works of art is an important factor in the overall study of the indoor climate of heritage buildings without mechanical ventilation and/or air-conditioning systems. In view of these concerns and the lack of studies on natural ventilation in heritage buildings, this study aims to analyse the performance of natural ventilation in the São Cristóvão Church in Lisbon, Portugal. For the preparation of this study, an analysis of the natural ventilation of this church was carried out by creating a model in the CONTAM software, and the indoor air quality was analysed based on different international standards and guidelines for carbon dioxide levels and air flow rates (ACH). Estimating the current ventilation strategy, an average ACH of 0.75 h−1 was estimated during the time the church is open, and an ACH of 0.15 h−1 was estimated during the time the doors were closed. In a yearly analysis, an average ACH of 0.30 h−1 was obtained. These air exchange values guarantee EN 16798-1 category I air quality for 72% of the year and category II air quality for 18% of the year. Different natural ventilation strategies were analysed: (a) three scenarios exploring different cross ventilation scenarios; (b) a scenario assuming that the church is closed all year round; and (c) a scenario estimating an increase in the number of visitors, giving an idea of the variations in human pollutants and possible consequences. Taking into account the air infiltration and the fact that masses, an occasional situation with a high number of visitors, are always held just before the church closes, it is guaranteed that carbon dioxide levels will never exceed the limit of 350 ppm above the outdoor values imposed by EN-13779, registering a maximum of 291 ppm.

Indoor Climate Monitoring in Office Buildings—Comparative Analysis of Two Office Buildings without Air Conditioning

Against the background of climate protection and the rising costs of a fossil-fuel-based energy supply, the interest in the energy performance and indoor climate of buildings in real operation is rising. This paper, therefore, deals with the indoor climate investigation of two medium-sized office buildings in Germany by taking measurements over a whole year. These relate to one new building and one refurbished building. Sensors of various types were installed and operated in a large number of office rooms, so that in total results are available for over 100 rooms, typically occupied by one or two persons. The analysis focuses on the indoor temperature in summer and the air quality in winter based on the CO2 concentration. The comfort classes according to DIN EN 16798 including the adaptive comfort approach are used as a basis to cluster the results. Both buildings have movable sun protection and openable windows but no facilities for active cooling. They, thus, represent a large number of existing ‘low tech’ office buildings in Germany and central Europe. The results reflect the respective building concepts but also show a wide range between the rooms due to the user preferences and behaviour. The refurbished building shows better results, especially in terms of air quality but also in terms of summer room temperatures. This underlines the benefit of the targeted measures as a result of an analysis of the deficits in the existing building before the refurbishment. The additional measures for decentralised mechanical ventilation and passive cooling are having positive effects. As part of the projects, further measures to improve the indoor climate were investigated in both buildings. In one case, this involved CO2 traffic lights to stimulate personal window ventilation in winter, and in the other, the use of newly developed individual ceiling fans supports convective heat dissipation on the human body during hot spells in summer. The positive effect could be demonstrated for both measures.

In-situ empirical validation of common indoor climate parameters in an inhabited multizone dwelling

Combined building indoor climate and energy simulation models only recently gained vast popularity and their application has been moving from the research community to a broader audience. Yet, in-situ empirical validation of this new generation of complex multi-purpose dynamic simulation models has lagged behind. Using a dynamic multizone building indoor climate and energy simulation model in Modelica with the IDEAS library and buoyancy driven airflow components (validated with CONTAM), this research presents model validation results and lessons learned from an in-situ empirical validation study of common indoor climate parameters (i.e., indoor air temperature (), relative humidity (RH) and CO2 concentration (CO2)) for an inhabited and mechanically ventilated case study dwelling in The Netherlands. The simulation results show that the latest generation of building indoor climate and energy models in Modelica have great ability to accurately predict common indoor climate parameters in multizone inhabited dwellings (provided that user behavior info is available). Evaluation metrics for the three studied parameters show excellent calibration criteria (i.e., MAE between 0.60–0.78 °C (), 3.5–4.6% (RH) and 88–181 ppm (CO2)) and the accompanying graphs corroborate the findings. In the event that no motion sensor data is available, statistically generated occupancy profiles prove good representative alternatives on the condition that basic info is available about the number of inhabitants and the inhabitants’ lifestyle. In-situ monitoring for empirical model validation proves to be a real challenge full of (un)foreseen obstacles.

Challenges and prospects for energy efficiency development in residential buildings

The multifamily housing stock in Russia has a high degree of wear and tear, low energy efficiency, and inadequate maintenance, which leads to over-consumption of energy resources. High energy intensity is related to the fact that energy equipment is obsolete, high heat and energy losses during transportation occur, energy is spent by enterprises and population unreasonably, buildings and constructions have high heat losses. The main reasons for the efficient use of energy in the building sector is to reduce the heating and hot water costs of building owners, improve the indoor climate of buildings, save taxpayers' money in order to use the saved funds in other areas, introduce energy efficient and renewable energy technologies, improve the air quality, reduce the negative impact on the environment and climate change Based on the above mentioned, the article examines the aspects of energy efficiency of residential buildings, namely identifying the problems of energy efficiency, the main parameters of the state programme of energy efficiency of residential and public buildings. An example of potential incentives, comprehensive and reasonable use of incentives, which can change the current situation in the shortest possible time, is presented.

Dependencies of the indoor climate on the course of the seasons and derivation of regressions from long-term measurements.

A building's indoor climate is an essential input variable for a variety of building physics computational models, simulations, and analyses. Precise knowledge of the indoor climate is necessary to minimize the risk of mold or moisture damage and is required to ensure minimum heat insulation standards in buildings. Detailed data are especially necessary for the progressive application of transient calculations, for example, concerning thermal comfort or energy consumption. While the properties of building materials and the (local) outdoor climate are known, only rudimentary information about the dynamic indoor climate is available. Most existing information in the literature about indoor climate is fairly general and forgoes a differentiation between climatic region, occupancy profile, and the utilization of rooms. In this paper, we report on indoor climate measurements in naturally ventilated apartments over a period of 1year. The measurement results complement the existing data to provide accurate indoor climate data in buildings. The measured values of indoor temperature and relative humidity serve to derive the dew point temperature and moisture load whereby dynamic time-dependent regression functions are determined for these parameters. The evaluations are carried out separately according to room use. The comparison of living rooms and bedrooms indicates a great influence of room use on the indoor climate in residential buildings. The determined indoor climate model can be used for the planning of buildings and simulations. The classification into living rooms and bedrooms makes it possible to take user behavior into account more realistically in building physics simulations. The minimum thermal insulation in residential buildings can also be checked and designed based on realistic data. The prediction interval describes the limits in which residential rooms are free of damage with a high probability. In this way, the indoor climate model describes an approach to examine and evaluate simulation results regarding condensation risk and mold damage in naturally ventilated rooms.

Predictive and probabilistic modelling using machine learning for building indoor climate control

For the last few decades, thermal comfort has been considered an aspect of sustainable building evaluation methods and tools. However, estimating the indoor air temperature of buildings is a complicated task due to the nonlinear behaviour of heating, ventilation and air conditioning systems combined with complex dynamics characterized by the time-varying environment with disturbances. This issue can be alleviated by modelling the building dynamics using Gaussian processes since it also measures the uncertainty bounds. The main focus of this paper is designing a predictive and probabilistic room temperature model of buildings using Gaussian processes and incorporating it into model predictive control to minimize energy consumption and provide thermal comfort satisfaction. We exploited the Gaussian processes’ full probabilistic capabilities as the mean prediction for the room temperature model and used the model uncertainty in the objective function not to lose the desired performance and to design a robust control scheme. We illustrated the potentials of the proposed method in a numerical example with simulation results.

Effects of Climate Change on the Future of Heritage Buildings: Case Study and Applied Methodology

Heritage buildings and the precious artworks contained therein, represent inestimable cultural and artistic evidence from the past that must be properly preserved for future generations. In the last decades, climate change has gained relevance and is becoming crucial to assess the building performance under such effect to provide timely mitigation actions to preserve our cultural heritage. In this regard, this paper outlines a method that combines different experimental activities and tools to forecast possible future risks due to climate change for the conservation of the artworks and provide its application in a relevant case study in Italy, the Duomo di Milano. In detail, the suggested method consists of the monitoring of the building indoor climate to validate a simulation model, defining possible future scenarios based on the Intergovernmental Panel on Climate Change (IPCC) projections, and evaluation of the future conservation risks of the main artworks. The results of the analysis carried out, show that for some artworks (e.g., stone sculptures, some organic materials, etc.), the conservation conditions will not worsen compared to the current situation, while for others (e.g., paintings, wooden objects, etc.) the risk of deterioration is expected to increase substantially. This study helps to understand how the future climate can affect the indoor environment of a huge masonry building and allow to plan targeted mitigation strategies aimed to reduce the future risks.

Performance of passive retrofit measures for historic buildings that house artefacts viable for future conditions

Retrofitting a building normally aims to achieve a higher quality indoor climate in terms of thermal comfort or in terms of air quality, as well as reducing the building’s energy consumption. Alternatively, in buildings that house artefacts, the application of retrofit measures normally aims to improve the indoor climate in terms of the artefacts’ conservation. However, the outdoor climate, which greatly influences the indoor climate of buildings, is changing significantly. Hence, it is obvious that when retrofitting a building it is of key importance to consider this change, especially in historic buildings that house high-valued artefacts.This paper aims to study the performance of several types of retrofit measures in historic buildings that house artefacts by considering climate change. A validated hygrothermal model of a 13th-century church was used coupled with future weather files and a risk-assessment methodology based on damage functions.It was found that passive retrofit measures can mitigate some of the negative impacts that climate change is expected to induce in historic buildings that house artefacts. However, these measures can also lead to the decrease of the conservation metrics. Consequently, ranges of thicknesses of the analysed retrofit measures that ensure the conservation metrics are presented.

Quantification of Air Change Rate by Selected Methods in a Typical Apartment Building

An important parameter that affects indoor climate of buildings and also ventilation heat losses and gains is the speed of air change between the outdoor environment and the interior of buildings. Indoor air quality is therefore significantly associated with ventilation. Quantification of air change rate is complicated, because it is impacted by many parameters, the most variable of which is air flow. This study focuses on the determination and comparison of air change rate values in two methods by quantification of the aerodynamic coefficient Cp = Cpe − Cpi, so-called “aerodynamic quantification of the building” and the methodology based on “experimental measurements of carbon dioxide”. The study describes and takes into account the effect of wind, building parameters and air permeability for the building using “aerodynamic quantification of the building”. The paper compares these calculated results with the values obtained from experimental measurements method of carbon dioxide in a selected reference room in apartment building and evaluates the accuracy of the prediction of the air exchange rate obtained by these methods. At higher wind speeds the values of air change rate with considering the effect of openings are closer to the values obtained based on experimental measurements of carbon dioxide and the difference between the values without considering the effect of openings increases significantly.

Field investigations of a smiley-face polling station for recording occupant satisfaction with indoor climate

The use of smiley-face polling stations has had a rapid growth as a means of automatically and efficiently collecting user satisfaction verdicts in airports, restrooms, museums, and retail. Their advantages are that they are low cost, efficient for both respondents and analysts, in addition to having higher response rates than other survey types. Their main disadvantage is the lack of control with who is voting, meaning both repeat voters and non-voters may lead to biased results. The aim of this study is to assess the representativeness and functioning of such publicly located satisfaction polling stations (SPSs) in an indoor climate setting, and to evaluate their potential for real-time evaluation of occupant's satisfaction with the indoor climate. We carried out continuous field tests in two office buildings for more than two months where the results of SPSs were compared with 473 survey results collected in 10 rounds during the tests. To assess how sensitive the instrument was to changing conditions, we deliberately changed temperature setpoints on selected days in one of the buildings. We found that the SPSs had a high and variable non-response bias which could result in a low accuracy for benchmarking of building indoor climate satisfaction. Results also showed a high correlation between SPS complaints and complaints recorded in the surveys for the thermal comfort aspect of indoor climate, including thermal comfort induced by temperature interventions. SPSs can provide valuable continuous recordings of the occupant's satisfaction with the indoor climate.

Engaging Building Automation Data Visualisation Using Building Information Modelling and Progressive Web Application

Abstract The integration of the building information modelling (BIM) and assets database has enabled a potential pathway for building stakeholders to add value to the building lifecycle management (BLM) processes. However, the obtaining, storing, processing, and distributing of data have not been ratified in a detailed and semantic manner in any official guideline. This paper suggests a framework for the efficient development of an interoperable visualisation of a building “digital twin” through an intuitive interface, to contribute to the idea above. The framework was applied in two case studies as examples, where rich visualisations of two buildings in the Kanta-Häme region of Finland were constructed using their architectural models and building indoor climate metrics. By constructing an engaging interface, relevant metrics and constant feedback from buildings’ occupants are gathered, meaningful data is selected, processed, and displayed to improve the facility management (FM) process. The yielded result is a progressive web application (PWA), where valuable sets of building performance data are visualised and a promptly communicable channel between owners/occupants and building system is delivered. Further development of this application in practice and research work is also proposed to harness the data-driven monitoring and automation in buildings to the greatest extent.

Long-term monitoring for indoor climate assessment – The association between objective and subjective data

To enhance indoor climate monitoring and indoor climate assessment, a better understanding of the collection and analysis of monitored data, over longer time periods, is necessary. The goal of this work is to improve long-term monitoring in order to arrive at better performance of building indoor climate, with the perception of occupants in mind. Indoor climate was monitored in an open plan office lay-out in two Case study office buildings, during two periods each. Indoor climate data was obtained at different resolution levels (locations) in the work environment. Additionally, information from the occupants was gathered using two methods: short, right-now surveys and wrist skin temperature measurements (biosensed data). In total, 160 subjective responses were obtained. Outcomes showed that measurement at a specific resolution level is required for representativeness. For the Case studies, this level depended on the office lay-out and could not be generalized. Correlations between perceived thermal comfort and objective data, either of the indoor climate or the biosensed data were moderate at best. Better applicability of the data was found when using it in combination with classification algorithms, obtaining predictions of higher accuracy (close to 65% for the group under investigation).

Effect of hygrothermal behaviour of earth brick on indoor environment in a desert climate

This study describes the experimental testing of the hygrothermal properties of the earth brick and the numerical analysis of the hygrothermal behaviour of a residential building in a desert climate in order to evaluate the effect of the earth brick on the indoor environment. The hygrothermal properties, i.e. thermal conductivity, specific heat capacity, equilibrium moisture content and water vapour permeability, were characterized to be used in the following numerical simulation of indoor environment. The numerical analysis was conducted by whole building simulations using EnergyPlus which can be used to simulate the indoor climate in buildings. An existing residential building was monitored for two days in summer in order to validate the accuracy of the model. The simulated results showed that compared with the fired brick, the earth walls reduce the amplitude of both indoor air temperature and relative humidity fluctuations, especially the maximum of relative humidity, due to both thermal inertia and moisture capacity of the earth bricks. Besides, the heating energy consumption results of the earth brick rooms were significantly lower than the fired brick rooms during the heating period.

Graphene enhanced thermoelectric properties of cement based composites for building energy harvesting

Cement based thermoelectric materials can convert the available ambient heat absorbed by the building surfaces in summer into electrical energy. These materials can have an impact on the improvement of indoor climate of buildings, reduction of energy consumption and energy harvesting applications especially in the urban areas. In this paper, the thermoelectric properties of cement based composites with graphene nanoplatelets (GNP) inclusions were reported for the first time. GNP-cement mixtures were prepared by planetary ball milling and compressed subsequently to form bulk composites. We report the maximum electrical conductivity of 16.2 Scm−1 and Seebeck coefficient of +34.0 µVK−1 in this work. Hall measurement was performed to determine the material type and carrier concentration. It was found that all specimen exhibit p-type semiconductor behavior. Thermal diffusivity measurements were carried out using laser flash measurement technique. The highest figure of merit 0.44 × 10−3 was achieved at about 70 °C. Enhanced thermoelectric properties of graphene nanoplatelets cement based composites have a promising prospect in the urban heat island effect alleviation, thus saving electricity consumption and energy harvesting.

Heat Stress in Indoor Environments of Scandinavian Urban Areas: A Literature Review.

Climate change increases the risks of heat stress, especially in urban areas where urban heat islands can develop. This literature review aims to describe how severe heat can occur and be identified in urban indoor environments, and what actions can be taken on the local scale. There is a connection between the outdoor and the indoor climate in buildings without air conditioning, but the pathways leading to the development of severe heat levels indoors are complex. These depend, for example, on the type of building, window placement, the residential area’s thermal outdoor conditions, and the residents’ influence and behavior. This review shows that only few studies have focused on the thermal environment indoors during heat waves, despite the fact that people commonly spend most of their time indoors and are likely to experience increased heat stress indoors in the future. Among reviewed studies, it was found that the indoor temperature can reach levels 50% higher in °C than the outdoor temperature, which highlights the importance of assessment and remediation of heat indoors. Further, most Heat-Health Warning Systems (HHWS) are based on the outdoor climate only, which can lead to a misleading interpretation of the health effects and associated solutions. In order to identify severe heat, six factors need to be taken into account, including air temperature, heat radiation, humidity, and air movement as well as the physical activity and the clothes worn by the individual. Heat stress can be identified using a heat index that includes these six factors. This paper presents some examples of practical and easy to use heat indices that are relevant for indoor environments as well as models that can be applied in indoor environments at the city level. However, existing indexes are developed for healthy workers and do not account for vulnerable groups, different uses, and daily variations. As a result, this paper highlights the need for the development of a heat index or the adjustment of current thresholds to apply specifically to indoor environments, its different uses, and vulnerable groups. There are several actions that can be taken to reduce heat indoors and thus improve the health and well-being of the population in urban areas. Examples of effective measures to reduce heat stress indoors include the use of shading devices such as blinds and vegetation as well as personal cooling techniques such as the use of fans and cooling vests. Additionally, the integration of innovative Phase Change Materials (PCM) into facades, roofs, floors, and windows can be a promising alternative once no negative health and environmental effects of PCM can be ensured.

Temperature-preference learning with neural networks for occupant-centric building indoor climate controls

Heating, ventilation, and air-conditioning (HVAC) are vital components in providing a comfortable indoor climate for the occupants of buildings. In commercial buildings, HVAC setpoints are set according to average comfort temperatures. However, individual temperature preferences may be different. The purpose of this study is to explore the means of making HVAC systems respond automatically to local occupant temperature preferences. To create an occupant-centric indoor temperature environment, we propose an online-learning-based control strategy together with its design process. Four essential variables from four domains—time, indoor and outdoor climates, and occupant behavior—are extracted to construct datasets for preference models. A neural network algorithm and corresponding hyperparameters are suggested to model temperature preferences. According to time-dependent setpoints learned from dynamic contexts, a set of specified rules is used to determine setpoints for HVAC systems. For a period of five months, the resulting learning-based temperature preference control (LTPC) was applied to a cooling system of an office space under real-world conditions. The four case study rooms consisted of typical office uses: single-person and multi-person offices. The experimental results indicate that occupant preferences in the individual rooms differ from each other in both time horizon and temperature levels. The results report energy savings of between 4% and 25% as compared to static temperature setpoints at the low values of preferred temperature ranges. Meanwhile, during LPTC, the need for occupant interventions for adjusting room temperatures to fit their preferences was reduced from four to nine weekdays a month to a maximum of one weekday a month.

Impact of climate change on cultural heritage: a simulation study to assess the risks for conservation and thermal comfort

Artefacts are prone to various types of decay depending on the indoor conditions of the building in which they are kept. Moreover, due to climate changes, the indoor climate of these buildings may significantly change, which can endanger their preservation. Hence, this paper studies the effects of climate changes on the indoor climate of heritage buildings and on the conservation of artefacts and thermal comfort of visitors. For this purpose, a validated hygrothermal model of a naturally ventilated historic church - Saint Christopher's in Lisbon coupled with climate change weather files were used to obtain future indoor conditions. Additionally, four other climates were simulated using the building model: Seville (Mediterranean climate), Prague and Oslo (Continental climate), as well as London (Oceanic climate). The obtained indoor climates were assessed using a statistical analysis based in several known indices, a risk-based analysis and an adaptive thermal comfort model.