Solar forecasting constitutes a critical tool for operating, producing and storing generated power from solar farms. In the framework of the International Energy Agency’s Photovoltaic Power Systems Program Task 16, the solar irradiance nowcast algorithms, based on five all-sky imagers (ASIs), are used to investigate the feasibility of ASIs to foresee ramp events. ASIs 1–2 and ASIs 3–5 can capture the true ramp events by 26.0–51.0% and 49.0–92.0% of the cases, respectively. ASIs 1–2 provided the lowest (<10.0%) falsely documented ramp events while ASIs 3–5 recorded false ramp events up to 85.0%. On the other hand, ASIs 3–5 revealed the lowest falsely documented no ramp events (8.0–51.0%). ASIs 1–2 are developed to provide spatial solar irradiance forecasts and have been delimited only to a small area for the purposes of this benchmark, which penalizes these approaches. These findings show that ASI-based nowcasts could be considered as a valuable tool for predicting solar irradiance ramp events for a variety of solar energy technologies. The combination of physical and deep learning-based methods is identified as a potential approach to further improve the ramp event forecasts.

Grid‐connected photovoltaic electricity production steadily grows at the margin of conventional power generation, but its management becomes more complex. To overcome this challenge, a transformation of variable renewable energy (VRE) resources into firm power generation is proposed. Drawing on insights from the International Energy Agency Photovoltaic Power System Task 16 case studies, it becomes evident that achieving nearly 100% VRE power grids that reliably meet demand year‐round can be economically viable through optimal VRE transformation. This transformation involves various traditional methods, e.g., storage, VRE blending, geographical dispersion, and load flexibility. However, overbuilding VRE capacity and controlled curtailment, acting as implicit energy storage, are now seen as essential prerequisites for this transformation. Nevertheless, aligning this vision with the current market rules poses a dilemma as it doesn't necessarily align with VRE producers’ interests. This predicament calls for a reconsideration of VRE market regulations. Current designs based on marginal energy production signals do not suffice. Instead, it is advocated for market rules grounded in the capacity of firmly enabled VREs rather than their energy output. Ultimately, the economic model should harmonize with the variability of VRE resources, rather than forcing VRE resources to adapt to existing market structures.

Indicators for quantitative assessment of drought risks in beech and Norway spruce forests: The application of climate models to forecast future forest development asks for quantitative drought-response relationships, with the term “drought” first needing a definition. The long-term data series of an intercantonal forest observation program allowed to test various drought indicators, to compare them and to derive quantitative relationships for beech and Norway spruce. For basal area increment of both tree species indicators of the site water balance (SWB) performed best. For beech mortality site water balance and several indicators basing on the ratio between actual and potential evapo-transpiration (ETa/ETp) were equivalent, whereas for spruce mortality ETa/ETp during the first 80 days of the season was the best indicator. With these indicators the average drought related growth reduction after 2003 – a year with extreme drought – was estimated to amount to 32% for beech and 37% for Norway spruce. Mortality of Norway spruce increased by 130%, whereas the estimates for the increase of beech mortality vary between 54 and 110%, depending on the indicator. The observed quantitative relationships for growth were applied to map drought responses of growth for Switzerland. The maps clearly show the dry regions of Switzerland (northern Switzerland, southern Jura foothills, Lemanic region, Valais and Rhine valley around Chur), where basal area increment of beech and Norway spruce was reduced by more than 40%.

State and development of drought in Swiss forests Climate scenarios for the 21st century for Switzerland show increasing temperatures and more frequent weather extremes and the risk of drought will become more important. The objective of the study was the calculation of indicators which allow the estimation and evaluation of drought risks on a regional scale. The site water balance and the ratio between actual and potential evapotranspiration (ETa/ETp) were used as indicators. They are closely related to vitality parameters of trees. For projections in the future were used the A1B climate scenario, which assumes a warming of 2.7 to 4.1°C in Switzerland, and three regional climate models (CLM, RCA, REGCM3), which predict different developments regarding precipitation and temperature. Historical time series between 1951 and 2012 and scenarios up to 2100 for different climatic regions were calculated. The indicators reproduce well the measured trends and the regional differences. In all regions there was in the past a trend to increased drought. The Geneva/ Vaud region as well as the western midlands and north Switzerland show the most pronounced changes. Projections with the CLM model (which reproduced best the historic trend 1981–2010 for Switzerland) show increasing drought and, in general, an increasing variability of the climate for the mid-century.

Climate change and the urban heat effect are expected to have a large influence on the energy consumption and thermal comfort of buildings. However, using meteorological data which incorporates effects of climate change and characteristics of cities is not currently a standard practice in building simulation. By default, data of nearby meteorological stations often outside cities are used. This may lead to important discrepancies between simulation results and actual energy consumption and/or indoor climate data for buildings in urban areas. These effects are analysed within building energy part of H2020 climate-fit.city project. First, adapted urban and future meteorological data modelled using the UrbClim model and standard meteorological data were compared. Second, these data were included within the Meteonorm software (version 7.3.2). This was carried out for current climates as well as for future scenarios (RCP 4.5 and 8.5, 2050) for the cities of Barcelona, Bern, Berlin, Bremen, Prague, Rome and Vienna. Like this Meteonorm includes a combination of urban and future climates accessible in a user friendly tool. In a third step the urbanized TMY data sets generated by Meteonorm were used to simulate energy consumption, peak loads and indoor climate conditions with models of several typical buildings. In this comparison we show a simulation for a multi-family house for current and future climates. The whole-year simulation runs were compared to the reference scenario – the standard TMY (available in Bern and Vienna). For current climates heating energy consumption is 10-25% lower within cities and cooling energy up to 60% higher (Barcelona). Even bigger changes are seen for future climates: Heating loads drop by up to 30% and cooling loads rise more than 100% (they are 2-3 times higher than heating loads in Barcelona by 2050).

The Climate-fit.City service (https://www.climate-fit.city) provides the best available scientific urban climate data and information for public and private end users operating in cities. Within the Climate-fit.City H2020 project, the benefits of urban climate information for end user communities was demonstrated, considering services in diverse domains (Climate and Health, Building Energy, Emergency Planning, Urban Planning, Active Mobility, Tourism and Cultural Heritage) to improve decision-making and to help end users to better address the consequences of climate change at the local scale. The socio-economic impact assessment performed in the Climate-fit.City project has demonstrated that, in all the cases, there are actual and potential added values in terms of public service effectiveness, economic impacts, policy innovation and social impacts. Further impact was also revealed in terms of raising awareness by end users, policymakers and the general public about climate change. These diversified impacts offer a variegated landscape of sub-areas and stakeholders that are touched upon by each climate service.