As energy standards focus on reducing energy use in new buildings, attention is drawn to the gap between the expected and actual building operation and energy performance. This performance gap can be associated with the building construction, its systems, its unbalanced operation, the assumptions on occupancy profiles during the design phase, or the users’ interaction with the systems’ operation and control. This work focuses on a nearly zero-energy (nZEB) single-family house located in central Denmark. The analysis of indoor environment and energy use is based on year-long data monitoring. The reasons for the deviation between the expected and actual energy use are suggested. The indoor environmental quality is analyzed to verify the compliance with the standards. The European recommendation for the yearly primary energy use of new single-family houses is 50 – 65 kWh/m2. For the current case, the simulation tool Be18 gives a result of 30.8 kWh/m2 for the design phase. However, the actual energy use is measured to be 58.2 kWh/m2. The sensibility of nZEBs to such imbalances can lead to houses that do not function as intended. It is thus crucial to investigate further the causes of these disparities in order to bridge the gap between expected and final energy use in dwellings.
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Research on nearly zero-energy buildings has addressed mainly the aspects of energy saving or technical and economic optimization, while some studies have been conducted on comfort and indoor air quality. However, the potential problems that may arise in low-energy buildings during the operational phase, and especially the risk of fungal growth, which can deteriorate the indoor environment and pose a health risk to the occupants, are yet to be extensively investigated. The present work intends to analyze previous research on microbial contamination in zero-energy buildings in order to identify the possible risks that may lead to fungal formation and the possible strategies to prevent the proliferation of molds. The methodology is based on a systematic literature review and subsequent critical analysis to outline perspectives on this topic. The main results indicate that high envelope insulation and inadequate ventilation are the leading causes of fungal growth in energy-efficient buildings. The need for more detailed regulation in this area is also highlighted. The study’s outcomes underline the need for more attention to be paid to the design and management of zero-energy buildings, aiming to achieve the reduction in energy demands while ensuring the occupants’ well-being.
Conservation of historic and cultural heritage poses great challenges, as the causes threatening the integrity of structures are becoming more frequent, including inadequate maintenance, the occurrence of exceptional events (such as floods and fires), as well as the exposure to increasing levels of air pollution. Furthermore, even during normal operation and in controlled indoor environments, the conditions can become favourable for the colonisation and development of harmful agents. The fungal contamination and growth on indoor building materials can alter the surfaces and deteriorate the building elements. In the present work, a preliminary investigation is conducted aimed at analysing the critical conditions for the proliferation and growth of different fungal genera or species, on commonly encountered materials in historic buildings. The study is carried out considering the climatic conditions of two locations, typical of northern and southern Europe, respectively. Possible solutions are suggested to limit the proliferation of microbiological contamination and growth and to prevent degradation phenomena of cultural heritage.
Buildings will play a significant role in providing a safe and efficient operation of the future energy system. The aim of this work is to investigate how typical cost-effective renovation packages contribute to energy consumption reduction as well as influence the energy flexibility in a Danish single-family from 1970s, and if simple rule-based controller can contribute in peak shaving strategy. By choosing the different renovation packages, the space heating demand can decrease between 34 - 64% and the flexibility time can increase between 200 – 500%. Depending on the cut-off period, the simple RBC of turning off the heating power can further reduce the heating consumption and contribute in reducing the morning load peak with small compromise on the thermal comfort level.
Today's HVAC systems in the building sector become more and more complex in order to fulfill the increasing standard of the indoor environment, which typically have many components, sub-systems, and controls.Commissioning is a quality-oriented process to verify and document that the performance of buildings and HVAC systems fulfill the defined objectives and criteria. This study demonstrates the commissioning process in a campus building in Denmark. By analyzing the monitored date from BMS and on-site measurements, some fault operations and controls in the HVAC systems are identified, for example, improper setpoint for heating and ventilation, fault location of temperature and CO2 sensors, too high return temperature for district heating, etc. A building simulation model is developed and validated in order to test the optimization strategies and evaluate the energy conservation potential. An energy saving ranges from 20%-42% is realized after the implementation of the optimization strategies.
The significant expansion of intermittent renewable energy sources can compromise the stability of energy grids due to the mismatch between instantaneous energy use and production. Buildings have a large potential for energy storage and demand-side management, which can offer energy flexibility to a Smart Grid system. Smart control of heating, ventilation and air conditioning systems is a great solution for improving flexible energy use, load shifting and power peak shaving. This numerical study compares the energy flexibility potential of three different heating and cooling systems implemented in a nearly zero-energy office building. The energy flexibility strategy consists in the modulation of heating / cooling indoor temperature set points according to an energy price signal. The energy flexibility assessment was performed based on the energy shifting ability, indoor thermal comfort level and economic benefits. This article establishes a better understanding of the flexibility potential of common and innovative heating / cooling technologies. Lindab Solus system has the highest load shifting ability with a flexibility index of 67.41%, followed by the radiator heating system, scoring a 59.92%, and the underfloor heating system with 56.65%. It is clear that the selection between different heating/ cooling systems can have a great impact on the energy flexibility of the grid system.
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