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A segmented dynamic dwelling stock model is proven useful for understanding the development and changes of ageing building stocks, which is highly relevant for renovation measures and estimates of energy use and emissions in aggregated building stocks. In this paper, such a model is developed further for detailed analyses of dwelling stock energy demand and exemplified for the Norwegian dwelling stock 1960–2015. The dwelling stock model simulates the development in stock size and composition and is combined with archetype-specific energy intensities to estimate the total energy demand. After calibrating the model results with statistics, the model is used to explore the phenomena and causes of historical changes. A large-scale improvement of the energy efficiency of the Norwegian dwelling stock has taken place through renovation and construction of new dwellings. A historical shift to more efficient energy carriers and heating systems has had an effect on energy savings in the system, of the same size as the effect of the improved energy efficiency of the stock. However, the total average energy savings per m 2 are offset by changes in user heating habits. A significant decrease in average delivered energy intensity per m 2 is only observed after the introduction of heat pumps. [ABSTRACT FROM AUTHOR]

A dynamic building stock model is applied to simulate the development of dwelling stocks in 11 European countries, over half of all European dwellings, between 1900 and 2050. The model uses time series of population and number of persons per dwelling, as well as demolition and renovation probability functions that have been derived for each country. The model performs well at simulating the long-term changes in dwelling stock composition and expected annual renovation activities. Despite differences in data collection and reporting, the modelled future trends for construction, demolition and renovation activities lead to similar patterns emerging in all countries. The model estimates future renovation activity due to the stock’s need for maintenance as a result of ageing. The simulations show only minor future increases in the renovation rates across all 11 countries to between 0.6–1.6%, falling short of the 2.5–3.0% renovation rates that are assumed in many decarbonisation scenarios. Despite this, 78% of all dwellings could benefit from energy efficiency measures by 2050, either as they are constructed (31%) or undergo deep renovation (47%). However, as no more than one deep renovation cycle is likely on this timeframe, it is crucial to install the most energy efficient measures available at these opportunities. [ABSTRACT FROM AUTHOR]

This paper presents a model based on dynamic material flow analysis, general in its principles and applied to the dwelling stock of Norway for exemplification. The algorithm at the core of the model is presented in the form of a pseudo-code and is described in detail. The driving force in the model is a population’s need for housing and the necessary input are retrievable from national statistics on population, often dating back to around 1800, and its prognoses up to 2050 or beyond. Technical parameters such as the dwellings’ lifetime and the renovation cycles are expressed by probability functions. Outputs of the model are the flows of construction, demolition and renovation; analysis of the renovation activity is given particular attention. The model shows how the renovation rates are a result of the need for maintenance of an ageing stock, and provides quantitative estimates of the present and future natural renovation rates, i.e. without specific incentives. The paper shows how to validate the model against statistics and other data sources, and how to use the model’s future projections on construction, demolition and renovation activities in scenario based analyses of dwelling stocks’ energy demand and greenhouse gases emissions. [ABSTRACT FROM AUTHOR]

Models describing long-term development in energy consumption or greenhouse gas emissions from building stocks commonly model the underlying development in the building stock's size and composition using simple, linear trends. Uncertainty is rarely discussed. This study explores the importance of uncertainty in input parameters in a dynamic model for the Norwegian dwelling stock that is presented in a recent publication and provides valuable insights in expected future quantities of renovation activity and how different segments of the stock are subject to renovation. By use of a sensitivity analysis and a scenario analysis the present study focuses on how uncertainty in model input parameters affect the modeling results and the robustness of results and conclusions. The sensitivity analysis did not lead to unexpected changes in results, and showed the dynamic model being mostly sensitive to changes in population and dwellings’ lifetime. Further scenarios with extreme input values for population and dwellings’ lifetime were considered in order to investigate the consequences of low and high renovation options. Results prove that previous main conclusions still hold: renovation rates at levels necessary to achieve policy targets in energy and emission savings seem unrealistic to be achieved when modeling the ‘natural’ need for renovation. [ABSTRACT FROM AUTHOR]

Highlights: [•] The article investigates the flexibility of an all-electric Net-ZEB using heat pump. [•] The article investigates the maximum onsite self-consumption in such Net-ZEBs. [•] The article studies the maximum grid relief that a Net-ZEB could offer to the grid. [•] The article presents different control strategies to realize these maximum limits. [•] The effect of these control strategies on the system performance is investigated. [ABSTRACT FROM AUTHOR]

Abstract: The term Net ZEB, Net Zero Energy Building, indicates a building connected to the energy grids. It is recognized that the sole satisfaction of an annual balance is not sufficient to fully characterize Net ZEBs and the interaction between buildings and energy grids need to be addressed. It is also recognized that different definitions are possible, in accordance with a country''s political targets and specific conditions. This paper presents a consistent framework for setting Net ZEB definitions. Evaluation of the criteria in the definition framework and selection of the related options becomes a methodology to set Net ZEB definitions in a systematic way. The balance concept is central in the definition framework and two major types of balance are identified, namely the import/export balance and the load/generation balance. As compromise between the two a simplified monthly net balance is also described. Concerning the temporal energy match, two major characteristics are described to reflect a Net ZEB''s ability to match its own load by on-site generation and to work beneficially with respect to the needs of the local grids. Possible indicators are presented and the concept of grid interaction flexibility is introduced as a desirable target in the building energy design. [Copyright &y& Elsevier]