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This paper analyses a multi-apartment residential building undergoing staged renovation during the heating season using real-time, hourly metered heat consumption data over two consecutive winters in a temperate-cold climate. The renovation is implemented in clearly identifiable phases, which enables an empirical, measure-by-measure assessment of changes in heating demand as works progress. The analysed interventions include insulation of basement heat distribution pipework, attic insulation, external wall insulat...

This paper analyses how designing the same single-family building to different energy performance standards affects its life-cycle costs. The study compares five design scenarios for one building, starting from the current national minimum energy performance requirement, moving through a typical nearly zero-energy building solution and an enhanced NZEB variant, and progressing towards a highly energy-efficient Passive House and a Passive House PLUS solution with on-site photovoltaic generation. Each scenario is ev...

Accurate solar power forecasting is essential for grid stability and efficiency. Precise generation forecasts help balance electricity supply and demand, prevent overloads, and support renewable energy integration. It enables to optimize bidding strategies and reduce penalties for imbalanced production. This study presents a solar power forecasting approach that integrates deterministic models with machine learning. The system utilizes the pvlip Python library for deterministic calculations. XGBoost-based machine ...

Wind and solar energy have become increasingly viable sources of clean, sustainable power, enabling more infrastructure to operate independently of traditional energy grids. To assess the reliability of these energy sources, it is essential to evaluate how regional climate conditions influence the generation potential of renewable energy. Since wind and solar power generation is inherently irregular, analyzing both fluctuations and regional variations is crucial for making optimal decisions that ensure the continu...

Updated normative documents within the Fit for 55 legislative package envisage increased dynamics in achieving European Green Deal goals, which are obligatory for EU countries. This directly applies to over 65 million energy-inefficient buildings in EU27 urban areas as well as heat supply systems. However, unified funding for long-term renovation programs is not planned. To respond quickly to diverse financing options with distinct conditions and target variables, a costly and time-consuming elaboration of detaile...

Properties of building materials include many properties, the most important are mechanical, thermal, chemical, and economic. The most important thermal properties that characterize the total heat losses and thermal inertia of materials are thermal conductivity and specific heat capacity. The first one describes the stationary heat transfer through the structures, but the second describes the ability to absorb and release the heat energy with temperature change dynamically, and it is related to a unit mass of the ...

An ambitious reduction in greenhouse gas emissions is set by the political initiative -The European Green Deal- and -Fit for 55- package. The municipalities, which carry out the strategic management of the district heating systems, will have to ensure the sustainable development of the territory in a way that includes a significant increase in energy efficiency both in the building stock and in the related district heating system. The aim of this research is to study and develop an easy-to-use methodology and an a...

The data from three solar thermal collector systems installed in dormitories of the University of Latvia in Riga are analysed in detail to obtain parameters that characterise the operation of such systems in real operation conditions in Riga, Latvia. All the systems were installed in 2019-2020 and the data for one full year is available for the study. The area and the power output for the observed solar thermal collectors are similar-63 m2 with 51 kW for each. The differences exist only in the orientation of the c...

Three photovoltaic (PV) systems with the identical solar panels, the same charge controllers, and similar loads, but with different used battery types: AGM deep-cycle, LiFePO4 and lead-carbon were installed in Riga, Latvia for a long-term monitoring and analysis of the operation efficiency and potential energy losses in batteries under real operation conditions. Results of one full year of monitoring are analysed in this paper resulting quantitative indicators during different seasons. During the wintertime with l...

Avoiding thermal bridges in the building envelope is one of the key elements for the reduction of energy consumption in buildings. Numerical calculations of heat flux through the joints of building structures are becoming very relevant in the past years due to the EU requirements for nearly zero energy buildings. The most problematic typically is windows installation perimeter, where thanks to fastenings of the frame to the loadbearing structure, linear thermal bridge forms. The use of numerical calculation of tem...

Polycrystalline photovoltaic (PV) panels of various orientations were installed in Riga, Latvia, for long-term monitoring and determination of the efficiency in real operation conditions depending on the environmental parameters. Results of the first couple of years of monitoring are summarised in this paper. Analysis of the available energy and environmental data allows for the quantitative estimation of actual efficiency depending on spatial orientation and following comparison with manufacturer?s values. The cl...

Typically, during design stage of a single-family house, only initial costs are taken into account, which are also discussed with the customer and optimized with the aim of reducing them. Long-term calculations are usually not made. At the same time, the calculation of global costs to design, build and operate the building show the real difference in expenses while living in this house. In the case of nZEB building the global cost approach becomes especially useful because of the strict energy demand requirements ...

The aim of this research is to analyse the thermal properties of different non-traditional insulation materials with low thermal conductivity and light weight that are made from Latvian local raw materials and are ?green? or are innovative and advanced materials. The studied materials are grouped depending on the production type and possible applications as follows: ? multi-layer combination of insulation materials, incl. low-emission surfaces; ? straw, cane, hemp, and birch wood fibreboard made from local raw mat...

This research work describes cost-optimal calculations for existing buildings of different categories and main building elements, as well as comparison with the existing energy requirements. Calculations are based on Directive 2010/31/EU and on the Commission Delegated Regulation (EU) No 244/2012 with the associated Guidelines. Those documents are used both ? for the calculation of cost-optimal energy performance for a whole building (MWh or kWh/m2 per year) and for the assessment of optimal U-value for different ...

The calculated energy efficiency and specified physical properties of building materials may change significantly during the initial years of a buildingпїЅs operation under real climatic conditions. Five small test buildings with different wall assemblies were built in Riga, Latvia to compare different building construction characteristics under Latvian climate conditions. The heating energy consumption, thermal transmittance, air relative humidity and other important energy efficiency and environmental parameters...