Buildings In Germany Research Articles

Coordinated price-based control of modulating heat pumps for practical demand response and peak shaving in building clusters

With a high share of renewable energy in the power grid, it becomes increasingly difficult to ensure a continuous balance between power generation and consumption, thereby endangering grid stability. A substantial opportunity to address this challenge and align the heating demand with intermittent power production is offered by space heating and domestic hot water, which account for 80% of the energy consumption in buildings. Further research on the control of building clusters is required, where peak load management of multiple buildings can ensure grid stability during peak hours and contribute to avoiding power outages. In this paper, a rule-based controller is presented, called Extended Price Storage Control+ (EPSC+), for the practical and flexible operation of heating systems in a building cluster. Under dynamic pricing, the loads of electric heating devices for the provision of space heating and domestic hot water are shifted by EPSC+ while accounting for peak load constraints. The performance of EPSC+ is evaluated in a nine-week winter simulation study with a building cluster of ten buildings in Germany. For comparison, a hierarchical model predictive controller (MPC) and a hysteresis two-point controller are employed as benchmarks. Results close to those of MPC are achieved by EPSC+by reducing the median peak load by 38.8% and median electricity costs by 15% compared with the hysteresis controller. In contrast to MPC, EPSC+ does not require models, forecasts, or optimization and is computationally inexpensive, rendering it more attainable for real-world implementation.

Circular Economy in Heat Supply Systems for Buildings: An Overview of the End of Life of System Components and Existing Evaluation Systems and Products

Abstract In order to achieve climate protection targets, many heating systems must be converted to renewable energies and more efficient systems. Most of residential buildings in Germany are heated with natural gas (50 %), 25 % with an oil. Around 45 % of the heating systems are older than 15 years, 20,5 % are even older than 25 years. Therefore, a high replacement rate is to be expected in the next few years. In the context of circular economy, the accumulating materials should remain in the material cycle. Some materials, such as metals, can be recycled easily. However, building services engineering, in particular heat supply, has become increasingly complex. This paper focuses on the state of the circular economy of heat supply systems for buildings. Firstly, a detailed examination of products utilized in heat supply systems is undertaken. Secondly, an assessment of the end-of-life scenarios for these components was conducted, considering disposal routes and recycling rates. Lastly, an evaluation of assessment systems fostering a circular economy regarding heat supply systems is performed. The aim of the work is to provide an overview of the state of the art with regard to circular economy in heat supply and thereby draw conclusions as to where potentials and obstacles exist.

How Not to Reduce Carbon Dioxide Emissions: An Unbalanced Focus on Energy Efficiency in Germany’s Building Rehabilitation Policies

Germany needs to reduce CO2 emissions from space heating in its old buildings to net zero by 2045 to fulfil its climate goals. However, direct CO2 reduction measures in existing buildings receive relatively little subsidy support from the federal government’s German Development Bank, compared to generous subsidies for energy efficiency measures. This interdisciplinary paper evaluates this phenomenon by comparing costs and CO2 abatement effects of ever higher energy efficiency measures, alongside the costs of direct CO2 reduction through heat pumps and onsite photovoltaics. It uses a set of carefully selected reports on the costs and benefits of renovation to a range of energy efficiency standards in three common types of multi-apartment buildings in Germany, updating these for 2024 construction, energy, and finance costs. The cost of the CO2 saved is extremely high with energy efficiency measures and absurdly high with the highest energy efficiency standards, up to 20 times the cost of CO2 abatement through other means, such as offsite renewables. This reduces markedly with onsite CO2 reduction measures. This paper sets this analysis in the context of asking what social, cultural, and discursive factors extol energy efficiency so highly that policy tends to thwart its own stated goal of deeply reducing CO2 emissions.

Development of a High-Resolution Indoor Radon Map Using a New Machine Learning-Based Probabilistic Model and German Radon Survey Data.

Radon is a carcinogenic, radioactive gas that can accumulate indoors and is undetected by human senses. Therefore, accurate knowledge of indoor radon concentration is crucial for assessing radon-related health effects or identifying radon-prone areas. Indoor radon concentration at the national scale is usually estimated on the basis of extensive measurement campaigns. However, characteristics of the sampled households often differ from the characteristics of the target population owing to the large number of relevant factors that control the indoor radon concentration, such as the availability of geogenic radon or floor level. Furthermore, the sample size usually does not allow estimation with high spatial resolution. We propose a model-based approach that allows a more realistic estimation of indoor radon distribution with a higher spatial resolution than a purely data-based approach. A multistage modeling approach was used by applying a quantile regression forest that uses environmental and building data as predictors to estimate the probability distribution function of indoor radon for each floor level of each residential building in Germany. Based on the estimated probability distribution function, a probabilistic Monte Carlo sampling technique was applied, enabling the combination and population weighting of floor-level predictions. In this way, the uncertainty of the individual predictions is effectively propagated into the estimate of variability at the aggregated level. The results show an approximate lognormal distribution of indoor radon in dwellings in Germany with an arithmetic mean of , a geometric mean of , and a 95th percentile of . The exceedance probabilities for 100 and are 12.5% (10.5 million people affected) and 2.2% (1.9 million people affected), respectively. In large cities, individual indoor radon concentration is generally estimated to be lower than in rural areas, which is due to the different distribution of the population on floor levels. The advantages of our approach are that is yields a) an accurate estimation of indoor radon concentration even if the survey is not fully representative with respect to floor level and radon concentration in soil, and b) an estimate of the indoor radon distribution with a much higher spatial resolution than basic descriptive statistics. https://doi.org/10.1289/EHP14171.

Obligations for Owners to Climate-Proof Buildings in Germany

Obligations for Owners to Climate-Proof Buildings in Germany

Towards a defossilized building sector with field tests in the lab: Review, development, and evaluation

The transformation process in the building sector towards future city concepts requires changes in our society that aim for significant emission reduction until 2045. Currently, buildings in Germany are constructed and operated in such a way that no changes need to be made to them for decades. Therefore, any upcoming changes that do not achieve the climate goals must be avoided immediately. However, making the optimal decision for a change is complex due to (a) multi-domain (e.g., design and control), (b) multi-scale (e.g., single-family building and urban energy system), (c) multi-stakeholder (e.g., users and practice), and (d) long-term implications (up to decades). Conventional testing facilities and methods do not account for the integration of (a)-(d). Therefore, their technology readiness level is limited by 6. This paper introduces an approach that aims at (1) a multi-domain and multi-scale approach by applying process systems engineering to the building sector and that aims at (2) stakeholder integration already in the research process by applying the living lab approach. We combine the two methods, yielding a field test in the lab infrastructure pushing the technology readiness level to 7–8. In all, it consists of five test benches (Refrigerant Cycle Lab, FlexFass, RT-Lab, Raumklimalabor, and InFis). This work focuses on the Refrigerant Cycle Lab. Its concept is based on two further Hardware-in-the-Loop test benches which are extended by a safety system that ensures automated operation dedicated to heat pumps with flammable refrigerants. In two case studies, we show that field tests in the lab allow multi-domain and multi-scale testing. Both aspects support accelerating the transformation process towards a defossilized building sector. In the next step, the combination of test benches at different locations is promising to reduce the need to set up identical experiments at different locations. In the long term, the laboratory is designed to include external stakeholders to avoid time-consuming iterations and can, therefore, save resources, time, and money for our complex transformation process.

Re-thinking energy justice to achieve a fair distribution of shared electricity from rooftop photovoltaics in a typical multi-apartment building in Germany: an interdisciplinary approach

An important development in decarbonising energy consumption is the installation of shared rooftop photovoltaics on multiapartment buildings. It is widely agreed that the distribution of this relatively cheap electricity should be “fair” to all the users, and simultaneously maximise local use, to reduce global CO2 emissions and local electricity grid load. Most technical studies model or investigate distribution patterns on this basis, but without critical reflection on the energy justice issues that arise in sharing a common electricity source. This study brings together two distinct disciplines to move this discussion forward: technical issues in distributing shared photovoltaic output; and philosophical issues of energy justice. It sets this within Bhaskar's philosophy of interdisciplinary science which shows why narrow, highly specialist disciplines are necessary and why their findings must be brought together to inform us about the actual world we live in. On the technical side, the study models an apparently fair distribution pattern for a shared photovoltaic system in a case study multiapartment building in Germany. It then interrogates the outcome in terms of four different strands of energy justice philosophy: Rawlsian, Wittgensteinian, pragmatic, and “theological” (stemming from the environmental justice movement). It finds that Rawlsian concepts provide a basis for a just sharing pattern but with serious anomalies, while Wittgensteinian, pragmatic, and theological energy justice concepts provide avenues for these anomalies to be mitigated. This comprehensive cluster of energy justice approaches is therefore very useful alongside technical expertise, in the ongoing development of shared rooftop photovoltaics in multiapartment buildings.

Evaluation of Renewable Energy Technologies in a net Zero Energy Office Building in Germany

Besides increasing requirements for the thermal insulation of buildings, renewable energy sources as photovoltaic-systems as well as heat pumps become more important in the building sector. Until now, there is no sufficient experience of the operation of these units in net zero-energy buildings. Due to this, Daikin Europe NV and Athoka GmbH initiated a test lab to analyse the operation in a daily office routine. To coordinate the power supply and demand of the building, an energy management system is used. To achieve an efficient heating and cooling the operation of two air-to-water and one air-to-air heat pumps was combined. Furthermore, the impact of high reflecting roof coating on the photovoltaic yield was analysed. For this reason, the effectiveness of the energy management system and the combined operation of the heat pumps are evaluated in this paper. In addition, the paper points out the central points for achieving the net zero-energy goal.

Restoration of historic gypsum masonry

AbstractIncompatibilities between the original substance containing gypsum in historically significant buildings and modern hydraulic repair materials have been known for over 80 years. However, as a result of expansion phenomena, a lot of culturally and historically valuable buildings in Germany have been irretrievably destroyed in recent decades. In a project of the Deutsche Bundesstiftung Umwelt, the question of which materials and which technologies are suitable for the renovation of masonry containing gypsum was investigated.

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.

Strategies for LEED-NC-Certified Projects in Germany and Results of Their Life Cycle Assessment

The aim of this study was to investigate strategies for the certification of environmentally friendly office buildings in Germany. A total of 39 LEED-NC gold-certified office space projects were ranked according to their “optimize energy performance” credit (EAc1) achievements from the energy and atmosphere (EA) category and divided into two groups: 13 projects (group 1) with the highest and 13 projects (group 2) with the lowest EAc1 achievements. Nonparametric statistics were used to evaluate the differences between groups 1 and 2. A two-stage nested analysis of variance test was used to evaluate the differences between the two groups in terms of their life cycle assessment (LCA). A comparison of the two groups showed that group 1 outperformed group 2 in the EA category (p < 0.0001). However, in the other LEED categories, the differences between the two groups were not significant (p ≥ 0.0761). As a result, group 1 outperformed group 2 in terms of overall LEED points (p = 0.0048). The LCA of EAc1 showed that group 1 enacted the lowest environmental damage when compared to group 2 (p = 0.0040). The environmental assessment of LEED-certified projects can help green building managers choose the most sustainable certification strategy.

5. Alternative pig farm buildings in Germany: Technical choices, production costs and marketing of pigs

5. Alternative pig farm buildings in Germany: Technical choices, production costs and marketing of pigs

Soil-structure-interaction effects on the seismic performance of a masonry building under geothermal power plants induced earthquakes

The earthquakes caused by the geothermal power plant (GPP) operation are a new phenomenon observed in recent decades. Low-to-moderate magnitude events with a high recurrence rate. This research focuses on the evaluation of the impact of modeling soil medium and its interaction with a masonry building on the overall performance of the whole system. In this regard, a typical masonry building in Germany is considered. A set of 11 ground motion records of induced earthquakes by the GPP activity is adopted. Two separate detailed 3D nonlinear structural models of the building are developed. In the first one, the base support condition of the structure is assumed to be fixed, while in the second case, the building, the underlying soil medium, and their interaction are simulated in an integrated model. By obtaining their responses to the earthquakes through the time history analysis approach, the structural damage level, as well as the comfort level of the occupants of the building, are evaluated. The outcomes show that the structural damage remains at a low level in both cases; however, consideration of soil medium slightly intensifies the damage level. Furthermore, in terms of occupant comfort, humans will suffer from significant disruption, especially when the effect of soil-structure interaction (SSI) has been taken into account. Finally, a relationship between the comfort level of the occupants and the intensity measure of the earthquakes is developed for both fixed base and SSI models.

Toward zero-emission buildings: a case study on a non-residential building in Germany using life cycle assessment and carbon sequestration of green infrastructure

Regarding greenhouse gas (GHG) emissions and further environmental impacts, such as acidification potential (AP), eutrophication potential (EP), and pollutants, the building sector plays an essential role in the global transformation toward a climate and environmentally friendly industry. In this paper, a non-residential building in Germany is analyzed regarding various emissions (GHG, AP, EP, pollutants, acoustic, light, and radiation) and the primary energy demand (PERT, PENRT) during its life cycle of 70 years. Life cycle assessment (LCA) according to DIN EN ISO 14040/14044 and DIN EN 15978 is used to determine and allocate the environmental impacts of the building. Building emissions are compared to the compensation potential of the green infrastructure onsite. Based on scenario analysis, recommendations to reduce the building emissions are given. The results show that there are emissions in every life cycle stage of the building. Using green instead of conventional electricity for operational energy reduces GHG emissions, AP, and EP by more than 90%. Emissions that already occurred can only be reduced or compensated slightly: the carbon sequestration of the building’s green infrastructure and its outdoor facilities can compensate nearly 6% of the total GHG emissions. Therefore, the authors claim that strategies to avoid, reduce and compensate emissions should take place in early planning phases to realize zero-emission buildings.

Fragility and comfortability curves development and seismic risk assessment of a masonry building under earthquakes induced by geothermal power plants operation

This research is an attempt to estimate the seismic risk of geothermal power plants (GPPs) operation on the masonry buildings located in the vicinity of these infrastructures through a probabilistic framework. In this regard, a typical masonry building in Germany is considered. In the first part, the fragility and comfortability curves of this building are established. For this purpose, a set of 30 ground motions recorded due to GPPs activity are used for performing elaborated three-dimensional nonlinear incremental dynamic analysis to construct the fragility and comfortability curves. In the second part of the research work, by using the Monte-Carlo simulation technique and adopting the hazard model capable of simulating both seismological characteristics and ground motion intensities, the required number of probable hazard scenarios are generated for different ranges of GPPs injection flow rates. Afterward, the seismic risk imposed on the masonry building is evaluated by considering the developed fragility and comfortability curves. The outcomes highlight that the risk of facing structural damage is not significant; however, the disturbance of buildings’ residents is highly probable and can lead to considerable seismic risk. In addition, in the close vicinity of the earthquake epicenter (less than 5 km), the estimated risk increases tangibly in comparison with the larger distances (more than 15 km).

Comfort and Economic Viability of Personal Ceiling Fans Assisted by Night Ventilation in a Renovated Office Building

An expected increase in the use of air conditioning by 2050 will significantly increase electricity demand and come at a cost to the environment. Implementing passive cooling strategies and focusing on personal environmental control systems (PECSs) could help to address this issue. While numerous studies have investigated the positive impact of PECSs on thermal comfort and energy savings, their overall economic benefit has been poorly addressed. We present an economic evaluation of personal fans for an office building in Germany. Building performance simulation was used to compare passive and active cooling concepts, and sensitivity analysis was performed for different climate scenarios. A cost-benefit analysis was carried out, including an assessment of investment and operating costs and the monetary value of relative performance. The transferability of comfort and productivity into costs is the novelty of this paper. The results showed that by supplementing night ventilation with personal fans, discomfort hours could be reduced by up to 50%. However, the initial investment of the fan is not compensated by savings in productivity losses compared to night ventilation alone. A reduction in the cost of the technology could help to economically offset the investment. The results contribute to the literature on the economic evaluation of a PECS by proposing a framework to motivate its implementation in buildings.

HVAC control in buildings using neural network

The energy consumption in buildings become the largest part of energy consumption worldwide, accounting for 40% of total global energy consumption and one third of the green house emission (Ahmed et al., Dec 2021). The optimization of building HVAC system require in many cases a thermodynamic model and mathematical solver which consumes a lot of hardware and time. However the data driven methods that presents 48% are often focusing on one type of HVAC systems (Grassi et al., May 2022). The real engineering problem is that the data driven methods are limited to specific systems and investigated for specific configurations. To overcome this problem, many machine learning solutions for optimized control data for HVAC are proposed. Those solutions are tested for real buildings in Germany. This new controller approach considers the effect of sequential inputs such as weather conditions, internal energy and time, and it consider a historical HVAC optimized data output. The investigation is done for CNN, LSTM, RNN-GRU, RNN-attention, and for each method we try to idealize the hyper-parameters and configurations. The goal of the study is to investigate the accuracy of machine learning routine on building optimization controlling and the ability to learn controlled and optimized data for different systems, to compare difference between generation of single output and multiple outputs, to decide the best inputs prepossessing, and to evaluate the extreme weather effects. This investigation proves that data control solution have limitation especially with extreme weather conditions but it can be improved by working on the pre-processing and different configurations.

Comparative Analysis of Resource and Climate Footprints for Different Heating Systems in Building Information Modeling

Buildings play an important role to meet Sustainable Development Goals, especially regarding the use of resources and greenhouse gas emissions. They are increasingly designed with energy-efficient solutions regarding their operations, while the related use of natural resources is still insufficiently considered. In this article, a methodology in Building Information Modeling is proposed to measure the resource and climate footprints of buildings’ heating systems. The methodology is applied to a case study building in Germany. The studied heating systems include a gas condensing boiler, ground-source heat pump, ground-source heat pump with a photo-voltaic system and air-source heat pump backed up with a gas boiler. Next to the operational energy, the production and transport of the heating systems were also studied. Results show that heating system operations have the largest impact and that the variant of ground-source heat pump combined with photovoltaics (GSHP + PV) has the lowest impact. In comparison with the gas boiler (GB), savings of 75%, 47%, 80%, and 84% are addressed to climate, material, energy, and land footprints, respectively, while the water footprint of GSHP + PV is 73% higher than that of GB.

Shear behaviour of infra lightweight concrete (ILC) without stirrups

ILC stands for “Infra” Lightweight Concrete, a versatile construction material that contributes significantly to building sustainability and opens up innovative architectural prospects. The prefix “infra” reflects a level of lightness that falls below the range of the structural LC in international standards. The novelty of ILC arises from combining such lightness (dry density ≤ 800 kg/m3) with both moderate strength and good heat insulative characteristics, rendering its application in monolithic cross sections without additional insulation layers feasible. This implies that complex multilayer façade systems including highly insulative materials can be substituted with a single layer of ILC, resulting in substantial improvements in terms of planning and construction simplicity, energy savings and recyclability. Recently, ILC has received great research attention, allowing for a better understanding of its physical and mechanical properties, which resulted in the successful construction of several ILC buildings in Germany. However, the structural behaviour of ILC has not been completely investigated and some structural concerns remain unanswered. This paper focusses on the diagonal cracking of ILC without web reinforcement as part of a comprehensive study into understanding the overall shear behaviour. 26 simply supported beams were tested until failure in 4-point bending configuration tests in order to study the role the concrete strength, the longitudinal reinforcement ratio and the a/d ratio play in the diagonal cracking of ILC. It was found that the excessive shrinkage of ILC significantly reduces the diagonal cracking load and results in rather wider cracks. Therefore, a design approach has been developed, where the excessive shrinkage impact was processed by reducing the tensile strength of ILC based on the shrinkage strain value. The diagonal cracking load seemed to be connected to the reduced tensile strength and the depth of the compressed zone, with no influence of aggregate interlocking or dowel action.

Comparative LCA study of wood and mineral non-residential buildings in Germany and related substitution potential

The construction sector is a central source of greenhouse gas (GHG) emissions. Reducing environmental impacts along the life cycle of buildings is therefore an important target. Given recent innovations in low-energy buildings and energy supply systems with low climate impacts, additional reduction potential can mainly be found in mitigating GHG emissions in other life cycle stages. The focus of mitigation has thus shifted to emissions related to material input, and comparative life cycle analyses of buildings constructed with different material types are becoming increasingly relevant in guiding regulations to achieve emission reduction targets. This paper performs comparative life cycle assessments for 48 non-residential buildings, comparing GHG emissions according to the current European standardised calculation methods. A substitution potential is introduced to evaluate the advantage of using timber as a building material. Furthermore, a comparative method is presented for assessing the substitution potential on the building level. The results show that the substitution potential for the construction of the studied buildings ranges from 5 to 48%. Specific substitution potentials are differentiated between four subcategories of non-residential buildings. The lowest substitution potential was identified for agricultural buildings and the highest for office and administration buildings. Moreover, the current research shows that the specific materials, construction, the geometry and design all affect the substitution potential of a building. On the basis of these values, it is possible to make projections regarding GHG reduction potential in the construction sector on a national scale.