Heat Gain Research Articles

Development and performance investigation of coffee husk-derived carbon-based nanofluid for solar thermal applications

Managing agricultural waste effectively is a serious concern, particularly in agrarian economies, where poor disposal practices cause environmental and public health problems. This paper discusses the synthesis of a carbon-based nanofluid from coffee husk char for solar thermal applications, utilising pyrolysis as an effective method for valorising agro-residue. The synthesis used the left-over solid residue during coffee husk pyrolysis after gaseous product extraction. The feasibility of the synthesized fluid for solar thermal application is studied by physical, chemical and optical characterisations. The synthesized fluid had a thermal conductivity of 0.87 W/mK and a pH of 10.26. The fluid was stable with a zeta potential value of −59.4 mV. The mean size of particles in the synthesized fluid was 6.24 nm. The optical characteristics of the synthesized fluid were studied from UV–Vis absorption spectroscopy. The solar-weighted absorption fraction of carbon-based nanofluid was 62.6 %, and that of deionised water was 12.3 %. When investigated with a solar simulator (at irradiance values of 700, 800, 900, 1000 and 1100 W/m2), the maximum improvement in photothermal conversion efficiency was 14.35 % at 1100 W/m2. At all irradiance levels, the sensible heat gain and the photothermal conversion efficiency were found to be greater than those of deionised water.

Investigating Factors Impacting Power Generation Efficiency in Photovoltaic Double-Skin Facade Curtain Walls

Photovoltaic double-skin glass is a low-carbon energy-saving curtain wall system that uses ventilation heat exchange and airflow regulation to reduce heat gain and generate a portion of electricity. By developing a theoretical model of the ventilated photovoltaic curtain wall system and conducting numerical simulations, this study analyzes the variation patterns of the power generation efficiency of photovoltaic glass for different inclination angles, seasons, thermal ventilation spacing, and glass transmittance in the photovoltaic double-skin curtain wall system. The results indicate a positive correlation between the surface temperature of photovoltaic glass and both ground temperature and solar radiation intensity. Additionally, photovoltaic power generation efficiency is generally higher in spring and autumn than in summer and winter, with enhanced power generation performance observed. At an inclination angle of 40°, photovoltaic panels receive optimal solar radiation and, consequently, produce the maximum electricity. Furthermore, as the ventilation spacing increases, the efficiency of power generation initially rises, reaching a peak at approximately 0.4 m, where it is 0.4% greater than at a spacing of 0.012 m. For a photovoltaic glass transmittance of 40%, the highest photovoltaic power generation efficiency is 63%, while the average efficiency is 35.3%. This has significant implications for the application and promotion of photovoltaic double-skin glass curtain walls.

Optical-thermal modeling and geographic analysis of dusty radiative cooling surfaces

Radiative cooling for energy conservation and harvesting has gained considerable attention worldwide in recent years. The optical and thermal characteristics of radiative cooling surface at outdoors is susceptible to dust soiling. Currently, limited research has been devoted to this problem. This work presents a model utilizing the beam envelope method and effective medium theory to investigate the optical characteristics of radiative cooling surfaces impacted by dust soiling. Subsequently, an optical-thermal coupling model is developed to investigate the spectral emissivity, average absorption/emission rates, and net heat gain of radiative cooling surfaces affected by dust soiling. The effect of dust soiling on the absorption of solar radiation is evident, with a substantial effect observed, but its impact on emissivity in the atmospheric window bands is comparatively minor. Meanwhile, it could be noticed that the mechanisms by which various material parameters of dust layers impact optical characteristics are different. In addition, the integration of the optical-thermal coupling model with EnergyPlus meteorological data and MERRA-2 facilitates an exploration of the geographical distribution of radiative cooling power variations induced by dust soiling across different regions in China. It is concluded that regions in China with a higher potential for radiative cooling often characterized by elevated dust deposition rates and low precipitation, rendering them more susceptible to the adverse effects of dust soiling. Effective cleaning significantly enhances both the optical and thermal characteristics of radiative cooling surfaces. The findings of this study offer a theoretical foundation for the enduring application of radiative cooling technology.

Ultralong Bistable, Electrolytic MnO2-Based, Electrochromic Battery Enabled by Porous, Low-Barrier, Hydroxylated TiO2 Interface.

Electrochromic (EC)battery technology shows great potential in future "zero-energy building" by controlling outdoor solar transmission to tune heat gain as well as storing the consumed energy to reuse across other building systems. However, challenges still exist in exploring an electrochemical system to satisfy requirements on both ultra-long optical memory (also called bistability) without continuous power supply and high energy density. Herein, an ECbattery is proposed to demonstrate ultra-long bistability (>760h) based on the reversible deposition and dissolution of manganese oxide (MnO2) without the addition of any mediators. A porous low-barrier hydroxylated titanium dioxide (TiO2) interface is incorporated to synergistically enrich Mn2+-affinity active sites for deposition and effectively reduce the electron transport barrier of MnO2 for dissolution, thereby significantly improving the reversibility, high optical modulation (60.2% at 400nm), and energy density (352mAhm-2). The modification strategy is also verified on the cathode-less button cells with a much higher average coulombic efficiency (99.9%) compared to the batteries without the porous hydroxylated TiO2 interface (74.6%). These achievements lay a foundation for advancements in both electrochromism and Zn-Mn aqueous batteries.

Evaluating the Role of Melanic Coloration and Environmental Conditions on Heat Gain among Patagonian Lizards (Liolaemus fitzingerii Group)

Evaluating the Role of Melanic Coloration and Environmental Conditions on Heat Gain among Patagonian Lizards (Liolaemus fitzingerii Group)

Parameter-input estimation of RC thermal models of buildings using unscented Kalman filter and nonlinear least square method

Effective building energy management (e.g. temperature control strategies) necessitates reliable and computationally efficient building thermal models. One type of them is the resistor–capacitor (RC) model. However, estimating model parameters and inputs (e.g. solar heat gain) simultaneously is challenging, especially when some of the temperature states are missing due to instrumentation limitations and/or sensor malfunctions. The present study utilizes unscented Kalman filter (UKF) and nonlinear least squares (NLSs) methods for parameters and input estimation of RC models with possible unavailable temperature states. The estimation procedure, mathematical operations and result analysis are presented in detail. To evaluate the capability of the method, two case studies were conducted. The first case study involved a simple, made-up RC model with known parameters, inputs and states, while the second case study used monitored data from a single detached house. The capability of the method was evaluated by comparing the estimated parameters, inputs and states to the corresponding true values in both study cases. The performance evaluation shows that the proposed method can effectively estimate RC model parameters and inputs, even with certain missing states. The proposed method can be employed for timely online updating of RC model parameters to improve response prediction.

Thermal performance of shaded roofs: investigating the impact of material properties and efficacy of building performance simulation

This research investigates the thermal performance of shaded roofs in the composite climate of Roorkee, India, by examining four shading materials (three opaque, one translucent) over an unobstructed roof for eight consecutive days. Using ‘Designbuilder’ software simulations and a mathematical model, the study meticulously triangulates experimental, simulated, and modelled data. The hourly temperature profile of the roof under different shades is analysed and the results showed negligible differences among opaque shading materials, while the translucent material significantly altered the roof’s thermal performance due to solar transmittance. Opaque shades reduced peak heat gain through the roof by up to 77% and 71.5% on cloudy and sunny days, respectively, and reduced nighttime heat loss by 40% and 33%, respectively. This research underscores the importance of considering shading material properties in sustainable building design and confirms the reliability of simulation tools. Highlights The study finds that in parasol roofs, the shading material's thermal properties do not impact the roof's thermal performance, but the solar transmittance does. The study also found that opaque shading could reduce the hourly peak heat gain through the roof by up to 77% and 71.5% on a cloudy day and sunny day, respectively, and reduced the nighttime hourly peak heat loss from the roof by up to 40% and 33%, respectively. Despite considering shading elements in BPS tools to be thermally inactive, the tools perform valid energy simulations.

Solar Water Heating System with Absorption Heat Transformer for Annual Continuous Water Heating

We show the performance of solar heating by coupling a Solar Water Heating System (SWHS) with an Absorption Heat Transformer (AHT) for annual continuous water heating. Solar Fraction (SF), Solar Heat Gain (SHG), and Auxiliary Heat (Qaux) were meticulously assessed for three Mexican cities located in the most characteristic climates (Saltillo, Toluca, and Tapachula). This rigorous assessment process ensures the reliability and accuracy of our findings. The potential reduction in net solar collector area (Ac) and storage tank volume (Vt) can be seen by comparing its annual performance to that of a conventional SWHS. Both configurations were designed to deliver the same hot water amount (0.019 kg/s, 1693.4 L/day, heating from 15.8 to 94.4 °C) and simulated using TRNSYS software version 16.01 concerning combinational systems. The results showed that SWHS-AHT achieved superior performance in solar water heating, achieving a higher SF (up to 99.6%) and SHG (up to 1352 kWh/m2-year) compared to the conventional SWHS. On the other hand, the SWHS-AHT achieved similar performance to a conventional SWHS with up to 60% less Ac. For instance, in Tapachula, a SWHS-AHT with an Ac of 150 m2 and a Vt of 18 m3 matched the performance of a SWHS with an Ac of 375 m2 and a Vt of 15 m3. Notably, both systems required the same Qaux. Thus, the Qaux requirement shows that SWHS-AHT is promising for industrial applications in Mexico, offering improved performance and a reduced footprint.

Reflective coatings: Enhancing building performance and sustainability

Reflective coatings stand at the forefront of sustainable construction, offering a powerful solution to industry challenges posed by climate change, resource scarcity, and rising energy costs. These innovative coatings significantly enhance energy efficiency, improve thermal comfort, and contribute to urban heat management by reducing buildings' absorption of solar heat. This leads to a decreased reliance on air-conditioning systems, resulting in substantial energy savings and a lower carbon footprint for building operations. Our comprehensive study examines these coatings' application on roofs, walls, and windows, confirming their effectiveness in maintaining cooler building interiors and reducing the demand on mechanical cooling systems. By meticulously analyzing materials, application techniques, and modeling methodologies, the paper elucidates the coatings' pivotal role in promoting environmentally responsible building practices. The findings reveal that reflective coatings have the potential to reduce solar heat gain by about 40 %. This reduction can lead to a corresponding indoor temperature drop of 2–4°C in naturally ventilated buildings or a decrease in cooling energy use in air-conditioned buildings, provided the air conditioning system is not undersized. These energy savings are particularly significant in urban environments, where widespread adoption could potentially lower ambient temperatures by approximately 1°C, thus addressing the urban heat island (UHI) effect more effectively. In conclusion, our research offers a quantified assessment of reflective coatings, emphasizing their value within the broader discourse of environmentally responsible construction. Their substantial potential to support urban sustainability objectives is evident, marking them as a promising avenue for future development and implementation.

Solar performance-driven urban development: the case of western Sydney, Australia

ABSTRACT Urban densification, a response to population growth, poses adverse impacts on built environments. Limited access to sunlight is one of these consequences. Solar radiation and daylight affect urban canyons in different ways, including thermal comfort and illuminance levels. A balance between summer and solar heat gain can alleviate solar thermal considerations. This becomes even more important in an urban context like Western Sydney with an air temperature of around 6 to 10 degrees hotter than Inner Sydney (during extreme heat events). Additionally, Western Sydney is predicted to absorb two-thirds of the population growth of the Sydney region. Nevertheless, the urban development trend in this region doesn’t seem to meet the requirements of an environmentally sustainable scheme covering solar geometry-based design principles. Therefore, this study aims to develop a general urban model based on the spatial analysis of the western Sydney suburbs and propose a novel integrated methodology to provide the optimal solar-based urban design solution. This process uses an evolutionary algorithm as a computational tool to optimize solar radiation and daylight levels in extreme weather conditions. Results offer the optimum value for a wide range of design parameters regarding solar geometry.

Experimental investigation of the effect of phase change material on backup time and equivalent energy consumption of domestic refrigerator

Load shedding is a significant problem in rural areas. During a power outage, the cabin temperature of a refrigerator increases owing to the heat gain. In practice, a door should be opened to load and unload refrigerator products, particularly when the power failure period is longer. The use of a phase-change material (PCM) in the refrigerator cabin restricts the increase in temperature and provides a backup time that reduces energy consumption. Door-opening tests are essential during a power cut-off time to investigate the reduction in backup time owing to door openings. This article presents an experimental investigation on the influence of PCM masses of potassium chloride (KCl), sodium chloride (NaCl), and sodium fluoride (NaF) dissolved in water on the backup time and equivalent energy consumption of a domestic refrigerator for closed and open doors according to the standards IS 1476 and IEC 62552:2015. The backup time of closed-door tests was significantly increased by the PCM for all masses, i.e., between 15 and 200 min in absolute terms and between 14% and 182% in relative terms. The backup time for the closed-door tests was 1.8–1.03 times longer than that for the door-opening tests. The backup time of door-opening tests decreased significantly owing to heat entering the cabin for all masses, i.e., between 50 and 10 min in absolute terms and between 45.45% and 3.23% in relative terms. The equivalent energy consumption of a refrigerator decreased with an increase in PCM mass. In closed-door tests, it varied from 0.55 to 0.41 kWh.6-1 h for the 0–1.75 kg mass of all tested PCMs. In the door-opening tests, the equivalent energy consumption increased owing to door opening. The equivalent energy consumption for the door-opening tests was 1.12–1.02 times larger than that for the closed-door tests.

Multi-objective optimization of buildings in urban scale for early stage planning and parametric design

Passive design of buildings in early design stage is essential for energy efficiency and sustainability. In this study, a streamlined tool for parametric study and passive design of buildings in urban scale considering thermal loads and natural lighting performance is presented, which markedly enhances the efficiency of early-stage urban planning. The tool is comprised of three sub-models, including (1) degree-month based annual building thermal load prediction model, (2) simplified climate modification model that takes into account the effects of building layout on solar heat gain and urban heat island, (3) multi-objective optimization algorithm NSGA-II, which optimizes both energy-saving and natural lighting performance. Model validation results show that this tool has an average error of 11.44% and 15.82% in simulating building thermal load compared with Dragonfly and CitySim, and has an average error of 9.9% in predicting average daylight factor compared with Radiance. Multiple optimization scenarios and sensitivity analysis in 10 typical climatic cities were conducted. It is found that in cold and hot climatic cities, it is more beneficial to set energy target as the optimization objective, meanwhile, establishing natural lighting as a constraint, rather than solely minimizing thermal loads. In contrast, the inherently lower thermal loads of buildings in milder climatic cities help to achieve both energy-saving and natural lighting goals, and it is also found that the increased thermal loss due to a higher window-to-wall ratio can be offset by employing thicker wall and roof insulation or by improving building layouts.

Thermodynamic modelling of low fill levels in cryogenic storage tanks for application to liquid hydrogen maritime transport

One of the key challenges in transporting liquid hydrogen (LH2) in bulk onboard carriers is the requirement for high performance insulation to reduce the heat transfer and cargo boil-off losses. After unloading their cargo, carriers on the return voyage may retain a small amount of liquid (heel) to keep tanks relatively cold, as well as to chill down to the tanks prior to cargo loading. Therefore, there is an aim to reduce net heat transfer into the tank while minimising the required volume of heel. While practices are relatively mature in the liquefied natural gas (LNG) industry, it is not clear how this may differ for future LH2 carriage. In this study, a new analytical, lumped-mass model was proposed to predict vapour stratification and tank warm-up. A 40,000 m3 double-walled LH2 spherical tank was considered with vacuum perlite and polyurethane foam (PUF) insulation, and the effects of tank pressurisation and fill level on cumulative heat gain were investigated. The model pointed to key differences between the two insulation types. Heat gain in the vacuum perlite tank was not predicted to be sensitive to changes in fill level, while heat gain in PUF tank was predicted to be less sensitive to pressurisation. In each case, pressurisation was predicted to enable reductions in heel boil-off which offset any associated increase in cumulative heat gain. In comparing LNG and LH2, the model pointed to a slower thermal response of the LH2 tanks. Consequently, the increase in inner shell temperature was not expected to lead to significant reductions in environmental heat transfer into the tank. The findings of this study point to potential operational differences in the management of LNG and LH2 heel during the ballast voyage as well as considerations for vacuum insulated tanks.

Component-based SHGC determination of BIPV glazing for product comparison

Building-integrated photovoltaic (BIPV) systems are intrinsically designed to generate electricity and to provide at least one building-related function. When BIPV modules act as glazing products in windows, skylights or curtain walls, their ability to control the transmission of solar energy into the building must be characterised by a Solar Heat Gain Coefficient (SHGC) or g value (also known as Total Solar Energy Transmittance – TSET – or “solar factor”). For the comparison of BIPV glazing products consisting of one PV laminate and possibly further, conventional glazing layers separated by gas-filled cavities, the procedures documented in international standards for architectural glazing (e.g. ISO 9050 and EN 410) form a suitable starting point. Easily implemented modifications to these procedures are proposed to take both optical inhomogeneity (if relevant) and extraction of electricity from BIPV glazing units into account. Geometrically complex glazing and shading devices, and light-scattering glazing layers, are outside the scope of the proposed methodology; SHGC determination for obliquely incident solar radiation is also excluded. For these cases, the experimental calorimetric approach documented in [ISO 19467:2017; ISO 19467-2:2021] is recommended.The paper also presents results and conclusions from an implementation exercise and sensitivity study carried out by participants of the IEA-PVPS Task 15 on BIPV. The cell coverage ratio in the PV laminate, the thermal resistance offered by the glazing configuration, the choice of boundary conditions and the effect of extracting electricity were all identified as parameters which significantly affect the SHGC value determined for a given type of BIPV glazing. A practicable approach to accommodate the great variety of dimensions typical for BIPV glazing is also proposed. These findings should pave the way for modifying the existing component-based standards for architectural glazing to take the specific features of BIPV glazing into account.

Adaptive integumentary features of beef cattle raised on afforested or non-shaded tropical pastures

We aimed to analyze the seasonal acclimatization process of Nelore and Canchim cattle raised on two production systems (non-shaded, NS, and integrated crop-livestock-forest, ICLF), based on the dynamics of the morphological and functional attributes of the hair coat and skin during winter and summer. The study was conducted in Brazil, in a low-altitude tropical climate region. A completely randomized 2 × 2 factorial design was adopted as follows: two production systems (NS and ICLF), two breeds (Nelore and Canchim) in a longitudinal structure, with measurements repeated over time through two stations (winter and summer). The experimental animals consisted of 32 Nelore (Bos indicus) and 32 Canchim (5/8 Bos taurus × 3/8 Bos indicus) bulls. The animals were equally distributed between two intensive rotational grazing systems. In both breeds, the hair coat was significantly thicker in winter but longer in summer, which increased epidermal protection. The Nelore bulls had shorter, wider, and thicker hairs, which are attributes that promote heat loss via conduction. The Canchim bulls showed significantly lower hair density and higher epithelium distance to sweat glands, which resulted in higher core temperature and respiratory rate. In turn, Nelore bulls had higher serum concentrations of triiodothyronine and lower serum concentrations of cortisol. However, Canchim bulls more frequently and intensely activated their thermoregulatory system and markedly adjusted their hair coat and hair features to reduce heat gain, especially in summer. Therefore, the anatomical plasticity and functional integumentary characteristics of Nelore and Canchim bulls reflect their acclimatization to tropical conditions.

Research on Residential Interior Design and Energy Saving Optimization with Sustainable Low-carbon Development

The escalating crisis of global warming, driven by the emission of greenhouse gases, poses a formidable challenge for humanity as a whole. Notably, the construction industry contributes significantly to the global greenhouse gas inventory. Consequently, prioritizing low-carbon construction assumes paramount importance in mitigating the pervasive impact of the greenhouse effect on a global scale. Such an endeavor stands as a crucial safeguard for ensuring the sustainable development of human civilization. Therefore, from the perspective of low- carbon building design optimization research is an important part of low-carbon building. From the perspective of architectural design, this paper summarizes that low-carbon building design should pay attention to following aspects: reasonable use of natural lighting and natural ventilation, reduce the carbon emission value of building use stage; Taking the transformation project of the former engineering Institute of Southeast University as an example, this paper probes into the effect of design optimization on reducing carbon emissions, and quantitatively studies the relationship between the design optimization of lighting, ventilation and envelope structure materials and the reduction of building carbon emissions. The Angle selection of roof skylight is studied from the Angle of day- lighting optimization, the size and position of facade opening and the strategy of natural ventilation path are studied from the Angle of ventilation optimization. The indoor ventilation further reduces the refrigeration energy consumption, which is 22.1% less than before the renovation, and the roof reduces the heat gain by 22%-32%.e.

The synergistic effect of multiple design factors on building energy consumption of office blocks: A case study of Wuhan, China

Design factors such as block morphology, building form and building envelope performance are key parameters affecting building energy consumption of urban blocks. However, the synergistic effect of multi-design factors on building energy consumption has not been studied in detail. This paper aims to investigate the synergistic effect of multi-design factors on building energy consumption of office blocks in Wuhan, China. This study employs field survey, satellite map and open street map to extract the typical building forms and construct parametric models of office blocks. Then, 81 representative scenarios considering the synergy of multiple design factors in office blocks are built. Then, based on the Rhino & Grasshopper parametric platform, a building energy assessment tool that considers the synergistic effect of multiple design factors is developed to simulate and record the building energy consumption of each scenarios. Finally, the synergistic effect of multi-design parameters on building energy consumption of office blocks is quantified using correlation and multiple linear regression methods. The findings reveal that the synergistic effect of multi-design factors on building energy consumption is 18.53 %. Building energy consumption for high-rise pavilion typology is saved by 9.64 % than multi-storey courtyard. The key design parameter combinations affecting building energy consumption in office block are building shape factor, solar heat gain coefficient, wall K-value, building width and window-wall ratio of west and east. This study contributes to a deeper understanding of the synergistic effects of multiple design factors on building energy consumption in office blocks and presents a scalable model that can be applied globally to promote sustainable urban development.

Thermal performance of phase-change wall of a hotel building under hot-summer and cold-winter climate

ABSTRACT In China, the energy consumption in the building sector has increased tremendously in the past decades. It is important to investigate advanced passive energy-saving technologies for buildings. By applying phase-change materials in walls, the peak cooling/heating load can be significantly reduced. In the present study, a numerical model of one-dimensional heat transfer within a phase-change wall was developed and solved by Matlab, which was successfully validated with published data. Subsequently, the model was used to simulate the thermal performance of a phase-change wall in a hotel building in Shanghai, China. Simulation results demonstrate that the performance of the phase-change wall is optimized when the phase-change material is applied to both sides of the wall. Year-round heat transfer is minimized using layers of paraffin (C16-C28) and capric acid (2 cm), with phase-change temperatures of 43℃ and 16.3℃, respectively. The PCM wall reduces inwardthe inward heat transfer by 26.9% compared with a common wall without phase-change material. The outward heat loss is also reduced by 15.7% during the heating season. This study demonstrates that the PCM wall can effectively reduce indoor heat gain in summerin the summer and heat loss in winterin the winter. The numerical model has proven to be feasible for optimizing construction design.

Enhancing energy efficiency of PCM wall in winter with novel PCM-DLCB coupling design

In order to enhance the thermal performance of the phase change material (PCM) wall during winter, a novel PCM and double-layer capillary bundles (PCM-DLCB) coupling wall is proposed. The PCM-DLCB wall utilizes the capillary bundle near the outer surface to capture solar energy during sunny winter days. The heat is then transferred to the capillary bundle near the inner surface through a circulating pump, promoting the melting of the PCM. Optimization and long-term operation comparison research were conducted using numerical simulation to investigate the potential of the PCM-DLCB wall to improve energy efficiency during winter. Five structural parameters, including the type of PCM, the position of the capillary bundle, the position and thickness of the PCM layer, the spacing of the capillary bundles, and the flow velocity in the capillary bundle, were selected as variables for structural and operation optimization. The optimization target was the accumulated heat gain from the inner surface of the wall. The research results indicate that: (1) The most suitable PCM is RT-18HC; (2) Placing the PCM layer between the double-layer capillary bundle yields better results compared to other arrangements; (3) Optimal energy saving is achieved when the outer capillary bundle is positioned 6 mm away from the outer surface and the inner capillary bundle is positioned 8 mm away from the inner surface; (4) The optimal thickness of the PCM layer is 10 mm; (5) The optimal flow velocity in the capillary bundle is approximately 0.04 m/s. Furthermore, long-term operation results based on a typical hot summer and cold winter climate zone reveal that the optimized PCM-DLCB wall provides a 7.80 % increase in indoor heat gain compared to an ordinary PCM wall during winter, and an 18.4 % increase compared to a wall without PCM.

Balancing the Energy Efficiency Benefits of Glazed Surfaces: A Case Study

Daylighting design is not only dimensioning glazed surfaces to provide sufficient natural light to an occupied space but also a method of analyzing how this can be achieved without unwanted effects, such as gains and losses of heat, glare, and variations in daylighting intensity at various indoor distances and levels. The case study presented in this paper highlights the energy consumed due to a group of windows with a large glazed area in an existing building located in a temperate continental climate area. The energy consumption results from supplementary artificial lighting required to maintain adequate illumination for indoor activities and to counterbalance heat loss during colder periods are evaluated. The analysis performed by modifying the glazed surface led to the identification of an optimum value of window dimensions for minimum energy consumption. The results of the case study highlight the fact that the evolution of the total energy consumption, evaluated as the sum of the energy consumption due to additional heating/cooling and the artificial lighting required to compensate for the reduction in natural light, is strongly influenced by the dimensions of the glazed surfaces, as well as the minimum level of lighting imposed by the regime of activities carried out in the building. Thus, the outcomes obtained in the research show that at lighting values below 500 lx, the total energy consumption is directly proportional to the glazed surface. From values of 500 lx for the illuminance level, the total energy consumption drops from 2730 kWh/year for a window height of 230 cm to 2399 kWh/year for a height of 110 cm, after which it starts to rise again, reaching a value of 2786 kWh/year for a height of 30 cm. This phenomenon is also found at values higher than 500 lx; accordingly, for an imposed lighting of 1000 lx, the minimum total consumption is identified at a window height of 150 cm. The case study presented in this paper clearly highlights a complex relationship between the height of the glazed surface and the energy consumption required to compensate for heating or cooling and the reduction in natural lighting. Lower window heights reduce heat loss or gain but also correspondingly increase the energy consumption of artificial lighting.