Energy performance certificates (EPCs) have gained increasing attention in recent years in policies and research. However, little attention has been paid to the consistency of EPC input data over time and the ability to assess EPC quality by comparing it with prior or subsequent EPCs. This study analysed the EPC input data from 52,000 Danish single-family houses with two or more EPC reports. In total, about 105,000 EPC reports were investigated. Statistical analysis of the building geometry and thermal building envelope revealed significant changes. The results show that the building envelope area varies nearly independently of the reported floor area. Furthermore, the U-values of the opaque envelope increased by 45

Historic buildings are often assumed to have poor energy performance, and energy optimization of the buildings is perceived as threatening their cultural values. This study tests these assumptions. First, it examines the energy performance of Danish historic apartment buildings (buildings constructed before 1950 with a high preservation value, according to the national SAVE system (Survey of Architectural Values in the Built Environment)). Second, it assesses the extent to which the energy improvements in the historic buildings conflict with their historic value. An analysis of energy performance certificates (EPC) in 13,000 Danish historic apartment buildings reveals that they perform no differently than apartment buildings with a low preservation value, with 46% of historic apartment buildings achieving an EPC rating of “C”. Nevertheless, significant potential for further energy improvements is identified. Expert interviews and three case studies indicate that typical interventions for enhancing buildings’ energy performance rarely interfere with its historic values. This is partly due to structural conditions where shoulder-by-shoulder location, high building compactness, and supply with district heating gives a beneficial foundation for a high energy performance. Potential conflicts between energy improvements and historic values exist but are often resolved through dialogue between local authorities and owners about the interventions.

Energy optimization of historic buildings is often perceived as a threat to their cultural values. This paper examines this assumption. Firstly, we assess the actual energy performance of historic apartment buildings in Denmark using a register-based approach with 20,000 historic apartment buildings of high preservation value. Secondly, we explore the potential for energy improvements in historic buildings by analyzing typical interventions that have been implemented to achieve an EPC label C. Thirdly, we discuss whether these interventions pose a threat to the preservation values of historic buildings and how local authorities might address this challenge. We present three examples of energy optimization in historic apartment buildings, ranging from step-by-step renovations to larger renovations and transformations of historic buildings. The study finds that historic apartment buildings perform at least as well as traditional buildings from the same period in terms of energy efficiency, and there is significant potential for further improvements. However, there are large variations across different types of municipalities. Finally, we observe that most interventions are based on conventional solutions with limited impact on preservation values. We discuss how more radical interventions can be managed through dialogue between local authorities, building owners, and consultants.

The global construction industry, a significant contributor responsible for 37% of greenhouse gas emissions (GHGe), necessitates immediate and relevant policies to reduce emissions. Consequently, several countries are implementing GHGe limit values in building regulations to initiate mitigation measures. To support this development and the efforts to mitigate GHGe, this study provides a method for defining a representative case sample of conventional practice and bottom-up Life Cycle Assessment (LCA)-based limit values for policy measures. Based on a dataset of 291 actual building projects, a representative case sample of 163 conventional case studies is defined, and their related life cycle GHGe is calculated with LCA, resulting in a variation from 8.3 to 11.8 kg CO2e/m2/year. Cumulative distribution functions are computed with share factors, which consider the construction activity in a country and reflect the physical output of completed construction work from which limit values are derived. A general limit value is calculated at 9.0 kg CO2e/m2/year, corresponding to the median where the ambition level targets 50% of new construction to perform mitigation efforts. Across building types, limit values vary between 8.2 and 11.5 kg CO2e/m2/year, and more ambitious limit values for residential buildings are derived starting at 4.9 kg CO2e/m2/year based on examples of best practice case studies. Comparing the general bottom-up limit value against top-down targets reveals a gap, suggesting a necessary increase in the ambition level. Yet, limit values should be introduced and gradually tightened to reach net zero in 2050 across several building typologies to support the adaptation of mitigation strategies.

The data presented were sourced from 34,884 commercial smart heat meters and 10,765 commercial smart water meters, spanning a timeframe of up to 5 years (2018–2022). All data primarily originated from single-family houses in Aalborg Municipality, Denmark. Furthermore, comprehensive building characteristics were collected for each building, where available, from the Danish Building and Dwelling Register (BBR) and Energy Performance Certificate (EPC) input data. This effort yielded an extensive pool of up to 86 distinct characteristics per building. All smart meter data were processed employing a well-established methodology, resulting in equidistant hourly data without any erroneous or missing values. The building characteristics derived from the EPCs were additionally filtered using rule sets to improve the data quality. This dataset holds substantial value for researchers involved in the domains of the built environment, district heating, and water sectors.

In order to reduce CO2-emissions it is necessary to reduce the energy use in the existing building stock significantly. Gadehavegard - a social housing built-up area consisting of 19 similar blocks of flats with nearly 1000 dwellings situated in Denmark - needed renovation and therefore a block was selected for testing an ambitious renovation that would result in a significant reduction in energy use and CO2 emissions. The ambition was to reach the German Passivhaus standard for the building, i.e. a very strict requirement, especially for a renovation project. The renovation included insulating the facades from the outside, replacing all windows, insulating the roof, installing decentralized mechanical ventilation systems with efficient heat recovery and a photovoltaic system on the roof. In addition, the balconies were included in the apartments by installing foldable glass facades. This paper gives a detailed description of the renovation project along with measurements of the energy use and indoor climate before and after renovation. Comparing the achieved results to the Passivhaus requirements show that the original goal is not achieved, however, the building fulfils the less strict requirements of the Passivhaus renovation certification EnerPHit and is still a very good example on how significant reductions in energy use can be achieved for these types of buildings. Results before and after renovation are compared using the energy signature and shows that heating energy consumption has been reduced by more than 50% even though indoor temperature on average has increased from 21.7 degrees C to 23.3 degrees C. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

In 1990, Technological Institute (TI) in Denmark made a benchmarking study of 92 typical multi-storey buildings covering 23 000 dwellings. The study included measurement data from the 1970s and the years after the energy crises. This study showed that over a period of less than 20 years a significant reduction in energy consumption took place. In a new similar study, TI and Aalborg University have analysed 62 buildings covering 18 000 dwellings including measurement data from the last 20 years. This time, the data covers a period with an increasing focus on the carbon-emission impacts of energy consumption. As opposed to the first benchmarking study, the new 20-years study shows that the heat consumption has been almost constant over the last 20 years. This paper presents a comparative study of the two sets of measurements and evaluates energy saving efforts and individual building energy performance. Furthermore, the paper compares two different ways of deriving benchmarks from the data and demonstrates how utilizing change-point models/energy signature as opposed to the more traditional mean annual values per heated area, significantly increases the usability.

The overall aim to reduce CO2 emissions has brought the energy requirements for new houses into focus. The question is whether the stepwise tightening of the energy requirements for new houses has had the expected impact on the actual realized energy consumption. In the news media, headlines at regular intervals state that new houses do not perform as expected with regard to energy consumption based on a simple comparison to the building class (energy frame). The gap is sometimes explained by a higher indoor temperature than used in the standard calculation or more generally by resident’s “careless” energy behavior. However, this may not be the full explanation and there may be other reasons for the difference. Or more specifically: Does the theoretical calculated energy demand, based on standard assumptions and without taking into account the effect of variations in e.g. hot water consumption, internal heat gains or construction faults, underestimate the actual energy consumption in general? As an example, the registered measured energy consumption for heating and hot water of approximately 800 new houses was compared to the calculated energy demand. The analyzed energy consumption data show that a significant share of the houses consumes more energy in a simple comparison with the theoretical energy frame based on standard assumptions. The objective of the study was to find and evaluate possible explanations/reasons for this gap between the theoretical calculated energy demand based on standard assumptions and the real-life registered measured energy consumption for new houses. It includes an evaluation of the possible impact on the energy demand caused by deviations from the standard assumptions for a series of parameters like indoor temperature, hot water consumption, internal heat gains, U-values, thermal bridges and ventilation rates.

Under current rules in the Danish Meter Order at least 40% of the total heating costs in multi-story blocks of flats should be distributed by metering the consumption in individual apartments. This fixed share is the result of a previous study that showed that 40% of the total heating costs were used for space heating, 35% for production and heat loss associated with hot water consumption and fmally 25% of heat losses in the heating system. It is interesting to investigate whether this distribution remains representative in both existing buildings, where older buildings still dominate, as in newer and future standard of blocks of flats. Intuitively, we would like to settle 100% of the costs attributable to space heating, by individual meters. Thereby, tenants will pay for their own consumption which encourages energy savings. This is an excellent method for electricity, gas and water but for heating it is a much more complex issue. For instance, if a pensioner wants or needs a higher indoor temperature the expenses will become disproportionate due to heat transmission through internal walls, floors and ceilings. This is particularly pronounced in well-insulated buildings where the heat loss to the outdoor climate constitutes only a small proportion of the total heating consumption. It is therefore interesting to investigate the consequences for the distribution of heating costs by differentiated indoor temperatures in both older and new multi-story apartment buildings. This paper describes an analysis of the possibilities regarding individual metering and fair distribution of heating costs in multistory apartment buildings. The overall conclusion of the analysis is that there are several significant problems related to this issue, and it becomes even more complicated when space heating only accounts for 30% in new buildings (2010 requirement) and 5-10% in future buildings (2020 requirement). (C) 2017 The Authors. Published by Elsevier Ltd.