• Energy Research

| openaire: EC/H2020/856602/EU//FINEST TWINS Funding Information: This work has been supported by the European Commission through the H2020 project Finest Twins grant No. 856602; and by the Estonian Ministry of Education and Research and European Regional Fund grant 2014-2020.4.01.20-0289. Additional support was acquired from the Estonian Research Council grant PSG739. Publisher Copyright: © 2023 Increasing use of volatile renewable energy sources causes challenges in balancing supply and demand. Therefore, demand-side flexibility has rising importance for system operators and balancing authorities. Flexibility management methods are needed to integrate loads like ventilation systems of different buildings (e.g., residential and commercial) into flexibility service. However, the available methods described in research papers require further development for implementation in practice. Heating and cooling systems have received much attention from researchers, but the potential of ventilation systems has been left out of focus. Therefore, this paper provides a complete set of novel flexibility management methods for ventilation systems created from an aggregator's viewpoint. The flexibility is quantified through capacity (e.i. the amount of power consumption that can be altered), forced ventilation rate duration, and the tendered price for the service. The proposed methods were tested on a building model constructed and simulated in IDA ICE. The data processing and flexibility management methods were applied in MATLAB. Two types of ventilation systems with different sensor configurations were considered: constant and variable air volume. Forced ventilation rate duration is calculated using energy and mass balance analysis where the root means squared error was 10 to 33 min, depending on the system type, measured parameter, and sensor location. The flexibility service pricing model was tested on the 2022 years' manual frequency restoration reserve (mFRR) activation and balance energy market data. Peer reviewed

Abstract As a part of the 2030 energy and climate policy discussion, the Estonian energy roadmap ENMAK 2030+ is being developed to set optimal national targets for 2030. Developing such a national roadmap requires solid evidence of which scenarios with varying ambition can be developed. This study looked at economic benefits, including tax revenue, job generation, and disposable net income per 1 M€ of investment, and energy savings on both an individual and national level. In addition, economic quantification for the three scenarios was carried out. The study relied on secondary data collection with validation of the data through a sample analysis and interviews with project stakeholders. The main findings show that in all 17 jobs per 1 M€ of investment in renovation were generated per year and direct tax revenue was between 32–33%, depending on the renovation project. Results revealed that over a 20 year period, there are essentially two national energy policy options: both the living quality and asset value brought about by integrated renovation at 160€/m 2 or alternatively, that brought about by non-energy efficiency repairs at 31€/m 2 . The study confirms that investment in energy efficiency is not only environmentally important but provides economic benefits on an individual and government budget level.

Abstract This study provides information about development of cost-effective facade solutions during the last 5 years and illustrates the importance of different variables such as accuracy of window models, construction costs, energy prices, interest rate and inflation. The cost-effective South, East and West facade solutions were triple windows with window-to-wall ratio 22–40% and external wall mineral wool insulation thickness 150–200 mm, whereas larger windows could be used in the North facade. The economic variables and construction price changes have had the largest influence on the analysis of cost-effective facade solutions. Lowest energy use was achieved with large quadruple windows and automated external venetian blinds with an advanced control algorithm. Wider market uptake of efficient window solutions could allow more architectural freedom from the point of view of energy-efficient and financially feasible facade design. Using detailed window models instead of standard windows did not influence the cost-optimal facade solutions, but had energy and load effects in both directions.

Local thermal comfort and draught rate has been studied widely. There has been more meaningful research performed in controlled boundary condition situations than in actual work environments involving occupants. Thermal comfort conditions in office buildings in Estonia have been barely investigated in the past. In this paper, the results of thermal comfort and draught rate assessment in five office buildings in Tallinn are presented and discussed. Studied office landscapes vary in heating, ventilation and cooling system parameters, room units, and elements. All sample buildings were less than six years old, equipped with dedicated outdoor air ventilation system and room conditioning units. The on-site measurements consisted of thermal comfort and draught rate assessment with indoor climate questionnaire. The purpose of the survey is to assess the correspondence between heating, ventilation and cooling system design, and the actual situation. Results show, whether and in what extent the standard-based criteria for thermal comfort is suitable for actual usage of the occupants. Preferring one room conditioning unit type or system may not guarantee better thermal environment without draught. Although some heating, ventilation and cooling systems observed in this study should create the prerequisites for ensuring more comfort, results show that this is not the case for all buildings in this study.

AbstractThis paper examines the variation of the PEFs for DH networks in Estonia. The Estonian average DH PEF as well as for DH networks with different configurations are calculated based on principles described in EVS-EN 15316-4-5:2007. The initial data for calculation of Estonian DH PEF is from Statistics Estonia. The calculation results are analyzed and compared with the existing DH PEF. The conclusive part consists of the observed compliance of valid PEF value and its determination principles with the definition and nature of PEFs. The main discrepancies are highlighted and analyzed. The possibilities to minimize or avoid them are given.

Abstract District heating (DH) offers the most effective way to enhance the efficiency of primary energy use, increasing the share of renewable energy in energy consumption and decreasing the amount of CO2 emissions. According to Article 9 section 1 of the Directive 2010/31/EU of the European Parliament and of the Council of 19 May 2010 on the energy performance of buildings, the Member states of the European Union are obligated to draw up National Plans for increasing the number of nearly zero-energy buildings [1]. Article 2 section 2 of the same Directive states that the energy used in nearly zero-energy buildings should be created covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced on-site or nearby. Thus, the heat distributed by DH systems and produced by manufacturing devices located in close vicinity of the building also have to be taken into account in determining the energy consumption of the building and the share of renewable energy used in the nearly zero-energy buildings. With regard to the spreading of nearly zero-energy and zero-energy houses, the feasibility of on-site energy (heat and/or electricity) production and consumption in DH areas energy (i.e. parallel consumption, when the consumer, connected to DH system, consumes energy for heat production from other sources besides the DH system as well) needs to be examined. In order to do that, it is necessary to implement a versatile methodological approach based on the principles discussed in this article.

Wood stoves are widely used in dwellings for space heating, however transient heat output and relatively large heat emission might cause problems with over-heating in new well-insulated buildings. This paper introduces a simplified power sizing method for the building integration of wood stoves which was compared to dynamic building performance simulations. The analysis showed that on average the simplified method predicted the temperature increase in the living room similarly to dynamic simulations. However, in some cases the difference was up to 60%, which is significant when carried forward to selecting the optimal stove heat capacity. Precise use of the simplified power sizing method requires accurate knowledge of the building structures and effective thermal capacity of the room with the wood stove. Typically, this kind of knowledge is unavailable when selecting a wood stove and the method needs to be developed further. These investigations confirmed that more knowledge of the occupant behaviour and preference on thermal comfort is needed.