Energy Balance Of Building Research Articles

Energy performance of buildings with on-site energy generation and storage – An integrated assessment using dynamic simulation

The European Union aims to achieve a nearly zero energy balance in buildings by 2020. The present study takes into consideration the passive systems of the building, energy demand, and energy generated by the on-site photovoltaic and storage system, and how they interact in different scenarios. The study also considers the energy demand from the grid and the surplus of renewable energy. The software EnergyPlus was used and the parametric sensitivity simulation method was applied, taking into account blinds operation, ventilation strategies, HVAC operation schemes and battery storage capacity, in 96 scenarios. The results highlight that there is great variability between the considered scenarios, highlighting the importance of sizing methodologies for the passive systems and the use of optimized home management algorithms. It was found that the use of batteries with higher storage capacity increases the demand-supply from the on-site PV energy but decreases the amount of energy injected into the grid. The design of the PV and battery system based on yearly integrated simulations allows for an optimized solution. This study also emphasizes the importance of knowing the expected occupancy during the design phase, as a significant input to the sizing methodologies of the storage capacity and on-site generation.

Need for Automatic Bypass Control to Improve the Energy Efficiency of a Building Through the Cooperation of a Horizontal Ground Heat Exchanger with a Ventilation Unit During Transitional Seasons: A Case Study

One of the ways to improve the energy balance of buildings is through the use of local, renewable energy sources, for example, ground air heat exchanger. This article continues the study on improving energy efficiency of an EAHX working in cooperation with a ventilation unit. In the previously reported study (Romańska-Zapała et al., 2017), performed during the summer of 2016, it was found that in the summer, the continuous operation of these exchangers is not optimal. Furthermore, there is a need for dynamic control of the ventilation unit’s fresh air source. This is due to changes in the exchanger’s operating status between heating and cooling, as a result of external temperature fluctuations. This article presents the results of in situ measurements of the horizontal, tubular EAHX which supports maintaining the desired temperature in a building by preheating or precooling the inlet air of the cooperating ventilation unit during transitional seasons of the climatic conditions of southern Poland. In particular, this article provides details on the experimental verification of the 2017 thesis regarding the ineffective work of an EAHX during transitional seasons. The influence of the exchanger on changes in the ventilation unit’s inlet air temperature is presented. Numerous, unfavorable changes were registered in the state of the exchanger’s work, either heating or cooling the flowing air, depending on the relation of outside air temperature to the achieved output air temperature. This indicated that the work of the exchanger was ineffective for buildings. The key to optimal, energy efficient EAHX – ventilation unit system operation during transitional seasons is the dynamic selection of a fresh air source depending on external conditions and the required output air temperature of the ventilation unit (air supplied to rooms), accounting for the increase of electric energy consumption for the fan drive during EAHX operation.

The Return of Spatial Dimension into Architecture

The aim of the paper is to explore and establish a base for a possible development of a more holistic and spatially-inclusive method for evaluating energy performance of buildings. This is to be achieved by envisioning building envelopes as arrangements of spatial zones, which could improve the overall energy balance of buildings but at the same time reduce the usage of construction materials and thus consumption of production energy and built-up space. The wall deconstructed in spatial zones, as shown e.g. in Antivilla by Brandlhuber-+, opens a series of questions about the future of existing building codes and certification tools. The potentials are discussed based on the aspects of flexibility, responsiveness, adaptability, replaceability and affordability. The analysis outlines the benefits of the inclusion of those paradigms in the definition of sustainable architecture, and at the same time exposes the lack of possibility to reflect their potential by the established certification criteria. The paper aims at opening the discussion about the limits and traps of quantifying architecture and calls for rethinking of established schemes of sustainability in building sector.

Monitoring system of an energy efficient school building

The paper presents details regarding the implemented monitoring system of heat loss, interior comfort and energy consumption particularities of an energy efficient school building in Romania. Despite the fact that there is an emphasis on energy saving and sustainability in the building industry legislation and policies, there are still too few examples of good practice at local level. Recent trends have brought changes in how designers solve specific details like thermal insulation thicknesses and use of renewable energy but further improvement is required for a more detailed understanding of the entire building's energy balance behaviour both on overall and specific details level. Therefore, a complex monitoring system was built in a carefully designed and constructed school building in order to collect relevant real-time data of every specific part of the thermal envelope, the HVAC systems and interior comfort parameters. The main purpose of the system is to highlight the order of magnitude of the differences between the design and the real-time values of the most significant parameters, the importance of each detail and also the need of further research development in this field.

Climate change impact on energy balance of net-zero energy buildings in typical climate regions of China

Net-zero energy building (NZEB) is widely considered as a promising solution to the current energy and environmental problems. The existing NZEBs are designed using the historical weather data (e.g. typical meteorological year-TMY). Nevertheless, due to climate change, the actual weather data during a NZEB’s lifecycle may differ considerably from the historical weather data. Consequently, the designed NZEBs using the historical weather data may not achieve the desired performance in their lifecycles. Therefore, this study investigates the climate change impacts on NZEB’s energy balance in different climate regions, and also evaluates different measures’ effectiveness in mitigating the associated impacts of climate change. In the study, the multi-year future weather data in different climate regions are firstly generated using the morphing method. Then, using the generated future weather data, the energy balance of the NZEBs, designed using the TMY data, are assessed. Next, to mitigate the climate change impacts, different measures are adopted and their effectiveness is evaluated. The study results can improve the understanding of climate change impacts on NZEB’s energy balance in different climate regions. They can also help select proper measures to mitigate the climate change impacts in the associated climate regions.

Adaptive solar shading of buildings

Adaptive solar shading systems have in comparison with the traditional systems of shading increased potential ability to improve the quality of the indoor environment and to increase the energy performance of buildings. Their extension allows all-around technological progress, but also the extensive application of large-scale glazing in building envelopes almost in all climatic regions. The literature review shows that the characteristics of the individual adaptive shading systems differ. Some have better performance in the sun protection or in improving the building's energy balance; others for example are better in glare elimination or in redistribution of daylight. The main purpose of this contribution is to provide a classification of the adaptive solar shading systems. In the article are compared merits and shortcomings of adaptive shading systems and are shortly analyzed assumptions of their wider application in central European climate conditions. Attention is also given to advantages and disadvantages, which brings the application of some kinds of adaptive solar shading systems. Several examples of adaptive shading systems are shown and briefly characterized.

Parametric Analysis of Buildings’ Heat Load Depending on Glazing—Hungarian Case Study

The share of cooling is rising in the energy balance of buildings. The reason is for increasing occupants’ comfort needs, which is accentuated by the fact that the number and the amplitude of heat waves are increasing. The comfortable and healthy indoor environment should to be realized with the minimum amount of energy and fossil fuels. In order to meet this goal, designers should know the effect of different parameters on the buildings’ energy consumption. The energy need for cooling is mainly influenced by the glazed ratio and orientation of the facades, the quality of glazing and shading. In this paper the heat load analysis was done by assuming different types of summer days and surface cooling, depending on the glazing ratio, shading factor and solar factor of glazing. It was proven that, for a certain parameter, the sensitivity of the heat load depends on the orientation and chosen summer day. If the glazing area is doubled, the heat load increases with about 30%. Decreasing the glazed area to 50%, the heat load decreases with about 10%. The heat load decreases with about 3% if the g factor is lowered with 25% or the shading factor is reduced with 60%.

Reusing Pruning Residues for Thermal Energy Production: A Mobile App to Match Biomass Availability with the Heating Energy Balance of Agro-Industrial Buildings

Using the pruning residues of woody crops can be beneficial in many ways (e.g., excellent energy balance, a net reduction in pollutant emission and a positive contribution to global warming control). This article describes the background work and development of a new support tool that will allow the user to know the amount and quality of pruning residue required to meet the energy requirements to heat both residential and agro-industrial buildings (e.g., greenhouses). Knowing the average amount of pruned biomass (t d.m. ha−1), the average lower heating value of wood (4.00 kWh kg−1) and the average efficiency of a woody biomass boiler (90%) enabled the overall available net energy yearly amount (kWh year−1) to be determined. This was compared to the overall energy requirements (kWh year−1) of agro-industrial buildings, which are a result of their main features (e.g., maximum heatable surface, building energy classification and the climatic zone). Depending on user needs, the tool suggests the amount of required biomass and, if not entirely available, what amount of fossil fuels are required to fulfill the energy requirement. The algorithm output was compared with the results of two case studies carried out on seven farm buildings and nine greenhouses. Knowing the amount and energy potential of the available biomass allows for planning and evaluation of the planned benefits.

Mathematical Models for Determination of Specific Energy Need for Heating and Cooling of the Administrative Building

According to the building energy balance, most of the resources are spent on maintaining a comfortable indoor microclimate. To estimate the energy resources rational use and to determine building energy efficiency, specific indicators are used per unit area and/or volume.In this paper, a comparative analysis of various approaches to determination of energy need for heating and cooling that have been used or are introduced in Ukraine and the peculiarities of different climatic data application is carried out. The differences in application of considered methods are established. The analysis of various averaging time intervals (monthly, daily average and hourly) for climatic parameters change in dynamic models during the heating period application influence on heating and cooling load change is carried out. Specific energy need has been established according to different methods and a comparison with the current normative values in Ukraine has been made.

Innovative electrochromic devices: Energy savings and visual comfort effects

Adaptive facades, like electrochromic (EC) smart windows, represent the next generation of glazing with dynamic modulation of transparency, to suitably modulate the daylight and solar energy entering buildings. A study is reported, dealing with the manifold effects of building integration of an innovative solid-state EC device, assessing effects on the building energy balance and daylighting performance, in terms of Useful Daylight Illuminance (UDI) and Discomfort Glare Index (DGI). All the analyses were carried out using the experimental results, reporting the main figures of merit of EC devices as an input for building simulations, in the EnergyPlus software.

Energy savings due to building integration of innovative solid-state electrochromic devices

The next generation of adaptive facades includes dynamic electrochromic (EC) windows: they can dynamically modulate the daylight and solar energy entering buildings by application of an external voltage. Windows play a pivotal role in the definition of the energy balance as well as environmental impacts of buildings. Emerging technologies are focused on the optimization of these building components. We carried out an interdisciplinary study dealing with building integration of an innovative chromogenic technology, consisting in a recently designed single substrate solid–state electrochromic device, developed by some of the authors, with excellent figures and a compact device architecture. The practical implications on the building energy balance were analyzed by means of suitable simulations, carried out in Energy Plus. A reference office building was equipped with different glass technologies on the façade (clear glass, solar control, electrochromic glasses) and located in different cities (Rome, London and Aswan) to also include climatic effects in the analysis. The EC technology here presented outperforms all the others, with overall yearly energy savings as high as 40 kW h/m2 yr (referred to window surface) in the hottest climates, assuming the clear glazings as benchmark. Daylighting performances were significantly improved using innovative solid-state EC devices, both in terms of Useful Daylight Illuminance (UDI) and Discomfort Glare Index (DGI). In the best case, 82.7% of hours achieved optimal illuminance conditions on an annual basis.

Development of weightage for criteria affecting in retrofitting of existing building in Higher Learning Institution with clean energy initiatives

Campus university building is the Higher Learning Institution (HLI) involves complex activities and operations, conserving the energy has become paramount important. There are several efforts taken by universities to improve its current energy use such as policy development, education, and adaption of energy conservation solution through retrofitting. This paper aims to highlight the importance of the criteria affecting in retrofitting of existing buildings with clean energy in order to achieve zero energy balance in buildings. The focus is given to the development of criteria for solar photovoltaic (solar PV), wind turbines and small-scale hydropower. A questionnaire survey was employed and distributed to the green building expert practitioner. Factor Analysis, Factor Score, and Weightage Factor were adapted as a method of analysis in order to produce the final result with weightage output for prioritization and ranking of the relevant criteria. The result performed assists to provide the stakeholders an overview of the important criteria that should be considered especially during the decision making to retrofit the existing buildings with clean energy resources. The criteria developed are also to establish a structured decision-making process and to ensure the selection of the decision or alternatives achieve the desired outcome.

Development of a nationally representative set of combined building energy and indoor air quality models for U.S. residences

Americans spend most of their time inside residences where they are exposed to a number of pollutants of both indoor and outdoor origin. Residential buildings also account for ∼20% of the primary energy consumed in the U.S. To provide a tool for future investigations of interactions between energy use and indoor air quality (IAQ) in homes across the U.S. population, we developed a custom set of nationally representative building energy and IAQ mass balance models that predict annual energy use for space conditioning and indoor concentrations of a number of pollutants of both indoor and outdoor origin across the U.S. residential building stock. The residential energy and indoor air quality (REIAQ) model framework is built in Python and integrates between EnergyPlus and a dynamic mass balance model. REIAQ utilizes historical weather data to predict hourly energy consumption, air change rates, and HVAC system runtimes, which are coupled with historical outdoor pollutant concentration data and assumptions for indoor emission sources and other factors to predict hourly indoor pollutant concentrations. Modeled indoor pollutants include PM2.5, UFPs, O3, NO2, and several volatile organic compounds (VOCs) and aldehydes. The REIAQ model set successfully predicted annual space conditioning energy consumption for the U.S. residential building stock within ∼2% of historical data. Modeled indoor concentrations, infiltration factors for outdoor contaminants, and indoor/outdoor ratios of each pollutant all matched closely with observations from prior field studies. Population-weighted annual average indoor pollutant concentrations were also used to estimate the chronic health burden of residential indoor exposures.

Combined heat pump-district heating network energy source

The article describes the innovative combination of the heat pump's operation with the heating network called as cHPNes. The heat pump's lower heat sources used so far are air, water or ground. Their efficiency is usually incoherent with the energy needs of recipients. In the period of the lowest temperatures of the source, we have the highest demand for heat in the supplied facility. A combination of the water heat pump and the heating network is aimed at increasing the energy efficiency (COP) of the heat source and indirectly increasing the participation of renewable energy in the energy balance of buildings. The essence of the new solution is the use of returning water in the heating network to supply the heat pump evaporator. The working medium temperature of the heating network on the return in the all-year cycle is stable and high, which allows further use of energy of the heating water on the return. These are the two main advantages of network water used as the lower heat source, allowing for stable and efficient operation of the heat pump with COP above 13. This solution is a response to the need to improve the energy efficiency of highly urbanized spaces.

Complex analysis of energy efficiency in operated high-rise residential building: Case study

Energy conservation and human thermal comfort enhancement in buildings is a topical issue of modern architecture and construction. The innovative solution of this problem makes it possible to enhance building ecological and maintenance safety, to reduce hydrocarbon fuel consumption, and to improve life standard of people. The requirements to increase of energy efficiency in buildings should be provided at all the stages of building's life cycle that is at the stage of design, construction and maintenance of buildings. The research purpose is complex analysis of energy efficiency in operated high-rise residential building. Many actions for building energy efficiency are realized according to the project; mainly it is the effective building envelope and engineering systems. Based on results of measurements the energy indicators of the building during annual period have been calculated. The main reason of increase in heat losses consists in the raised infiltration of external air in the building through a building envelope owing to the increased air permeability of windows and balcony doors (construction defects). Thermorenovation of the building based on ventilating and infiltration heat losses reduction through a building envelope allows reducing annual energy consumption. Energy efficiency assessment based on the total annual energy consumption of building, including energy indices for heating and a ventilation, hot water supply and electricity supply, in comparison with heating is more complete. The account of various components in building energy balance completely corresponds to modern direction of researches on energy conservation and thermal comfort enhancement in buildings.

Glazing’s techno-economic performance: A comparison of window features in office buildings in different climates

The use of glass in buildings has a considerable impact both on comfort levels and energy performances, since glazed components protect from external environmental conditions, provides daylighting, view and also ventilation if they are openable. Starting from the second half of the 19th century, the architectural design used to give an increasingly important role to the glass, particularly in non-residential buildings, almost in every kind of climatic conditions. In this context, the present work aims to assess the techno-economic performance of glazing with various thermophysical and optical properties and different glass/wall ratios, coupled with internal/external shading systems, considering the application on an office building in 3 different representative European climates. The obtained results demonstrate that there is a negative impact of solar gains on the yearly energy balance of modern office buildings, where thermally-insulated envelopes enhance overheating even in cold climates. Because of this, the most reasonable solution to decrease the yearly energy consumption is to limit the amount of glazing or to use external solar shading devices. It can be also stated that, under a global-cost perspective, the best cost-effectiveness is achieved using a solar control glazing without any shading. If, however, the cost of discomfort due to glare is accounted, the use of solar shading devices emerges as the most convenient option in all analysed cases.

Impacts of parameter values interactions on simulated energy balance of residential buildings

In this study we use dynamic simulation to explore the interactive impacts of different uncertain parameter values in energy balance modelling of existing and improved variants of a Swedish multi-storey residential building. We modelled variations as well as interactive influence of different simulation assumptions and parameters encompassing outdoor microclimate, building thermal envelope and technical installations including household equipment. The results indicate that the interactive influence of the parameters on calculated space heating of buildings seems to be small and relatively more evident for a low-energy building than for a conventional building. The influence of the interactions between the parameter combinations becomes more evident as several parameters are varied simultaneously. The results also indicate that calculated space heating demand of a building is noticeably influenced by how heat gains from household equipment and technical installations are modelled. The calculated final energy for space heating for the analysed building versions varied between 13-43% depending on the energy efficiency levels for household equipment and technical installations as well as their interactions with other parameter values variations. This study shows the importance of appropriate input parameters and assumptions for building energy balance calculation.

The impacts of a dynamic sunlight redirection system on the energy balance of office buildings

The aim of this work consisted in investigating the potential of an advanced dynamic daylighting system, designed to provide higher work-plane illuminance levels deeper into the space and assess its impact on the building's energy balance. The device utilizes an array of movable mirrors capable of tracking the daily movements of the sun and projecting the reflected sunlight toward specified fixed positions onto the ceiling. This paper builds on the authors’ previous work by implementing a solar tracking algorithm developed to calculate the position of the mirrors in 3D space and the area of the reflected sun-patches on the ceiling on an hourly basis.

Comparing energy performance of different semi-transparent, building-integrated photovoltaic cells applied to “reference” buildings

Semi-transparent, building-integrated photovoltaics (BIPVs) are receiving significant attention by several research groups, given their increasing efficiencies combined to improved visual performance (being cell transparency and color rendering index, two key features to ensure their widespread use). Several technologies have been developed in the last years, based on the use of amorphous silicon cells, Cu(In,Ga)Se2 (CIGS) cells, organic PV cells, photoelectrochemical (DSC) cells, and perovskite-based cells. Each technology has pros and cons, but among them the two most reliable and promising seem to be the first one (ηSTC= 3-6% and Tvis= 7-40%) and the last one (ηSTC= 6.6% and Tvis= 42.4%). The second, in particular, may be processed so to appear neutrally colored, resulting in a substantially gray glass, while the first one, absorbing nearly all the blue-green radiation, presents an orange-brown coloration. The paper investigates how the use of both technologies affects the energy balance of buildings. For this purpose the EnergyPlus platform was employed and two validated reference buildings were used for comparison (one residential and one office building). Energy yield due to BIPV technologies, variation in heating and cooling loads due to cell transparency, and implications on visual comfort and on artificial lighting usage are finally discussed.

Evaluation of building heating loads with dimensional analysis: Application of the Buckingham π theorem

A detailed assessment of building energy performance requires a large amount of input data concerning building typology, environmental conditions, envelope thermophysical properties, geometry, control strategies, and several other parameters. Notwithstanding, the use of specialized software tools poses many challenges in regards to the retrieval of reliable and detailed information, setting a steep learning curve for engineers and energy managers. To speed up the preliminary assessment phase, it might be more convenient to resort to a simplified model that allows the evaluation of heating energy demand with a good level of accuracy and without excessive computational cost or user expertise.Dimensional analysis is a means of simplifying a physical problem by appealing to dimensional homogeneity to reduce the number of relevant variables. In this work, the authors investigated an alternative approach to assess the thermal energy demand of a high-performance-non-residential building. It was possible to define some dimensionless numbers that synthetically describe the links between the main characteristic parameters of the thermal balance by applying the Buckingham π theorem. After a detailed description of the Buckingham π theorem and of its application concerning the evaluation of the building energy balance, the authors identified nine “ad hoc” dimensionless numbers. The proposed methodology has been validated by the comparison of the heating energy demand calculated by detailed dynamic simulations carried out in TRNSYS according to the standards and laws of building energy requirements in seven different European countries. Applying a set of criteria, it was possible to employ a dimensionless number to determine, immediately and without any calculation or use of steady/dynamic software, the heating energy demand with an reliability >90%.