Integration of Micro-Cogeneration Units and Electric Storages into a Micro-Scale Residential Solar District Heating System Operating with a Seasonal Thermal Storage

A micro-scale district heating network based on the operation of solar thermal collectors coupled to a long-term borehole thermal storage is modeled, simulated and investigated over a period of five years. The plant is devoted to covering the domestic hot water and space heating demands of a district composed of six typical residential buildings located in Naples (southern Italy). Three alternative natural gas-fueled back-up auxiliary systems (condensing boiler and two different technologies of micro-cogeneration) aiming at balancing the solar energy intermittency are investigated. The utilization of electric storages in combination with the cogeneration systems is also considered with the aim of improving the self-consumption of cogenerated electric energy; heat recovery from the distribution circuit is also evaluated to pre-heat the mains water for domestic hot water production. The performances of the proposed plant schemes are contrasted with those of a typical Italian decentralized heating plant (based on the utilization of natural gas-fueled non-condensing boilers). The comparison highlighted that the proposed configurations can decrease the primary energy consumption (up to 11.3%), the equivalent emissions of carbon dioxide (up to 11.3%), and the operation costs (up to 14.3%), together with an acceptable simple pay-back period (about 4.4 years).

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Overview of Solutions for the Low-Temperature Operation of Domestic Hot-Water Systems with a Circulation Loop

Energies ◽

10.3390/en14113350 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3350

Author(s):

Theofanis Benakopoulos ◽

William Vergo ◽

Michele Tunzi ◽

Robbe Salenbien ◽

Svend Svendsen

Keyword(s):

Low Temperature ◽

Heat Loss ◽

District Heating ◽

Heating System ◽

Hot Water ◽

Heating Power ◽

Circulation Loop ◽

Space Heating ◽

District Heating System ◽

Domestic Hot Water

The operation of typical domestic hot water (DHW) systems with a storage tank and circulation loop, according to the regulations for hygiene and comfort, results in a significant heat demand at high operating temperatures that leads to high return temperatures to the district heating system. This article presents the potential for the low-temperature operation of new DHW solutions based on energy balance calculations and some tests in real buildings. The main results are three recommended solutions depending on combinations of the following three criteria: district heating supply temperature, relative circulation heat loss due to the use of hot water, and the existence of a low-temperature space heating system. The first solution, based on a heating power limitation in DHW tanks, with a safety functionality, may secure the required DHW temperature at all times, resulting in the limited heating power of the tank, extended reheating periods, and a DH return temperature of below 30 °C. The second solution, based on the redirection of the return flow from the DHW system to the low-temperature space heating system, can cool the return temperature to the level of the space heating system return temperature below 35 °C. The third solution, based on the use of a micro-booster heat pump system, can deliver circulation heat loss and result in a low return temperature below 35 °C. These solutions can help in the transition to low-temperature district heating.

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Advanced Control of a District Heating System with High Residential Domestic Hot Water Demand

E3S Web of Conferences ◽

10.1051/e3sconf/202016001004 ◽

2020 ◽

Vol 160 ◽

pp. 01004 ◽

Cited By ~ 1

Author(s):

Stanislav Chicherin ◽

Lyazzat Junussova ◽

Timur Junussov

Keyword(s):

Energy Demand ◽

Energy Use ◽

District Heating ◽

Heating System ◽

Primary Energy ◽

Hot Water ◽

District Heating System ◽

Domestic Hot Water ◽

Extreme Load ◽

Flow Controller

Proper adjustment of domestic hot water (DHW) load structure can balance energy demand with the supply. Inefficiency in primary energy use prompted Omsk DH company to be a strong proponent of a flow controller at each substation. Here the return temperature is fixed to the lowest possible value and the supply temperature is solved. Thirty-five design scenarios are defined for each load deviation index with equally distributed outdoor temperature ranging from +8 for the start of a heating season towards extreme load at temperature of -26°C. All the calculation results are listed. If a flow controller is installed, the customers might find it suitable to switch to this type of DHW supply. Considering an option with direct hot water extraction as usual and a flow controller installed, the result indicates that the annual heat consumption will be lower once network temperatures during the fall or spring months are higher. The heat load profiles obtained here may be used as input for a simulation of a DH substation, including a heat pump and a tank for thermal energy storage. This design approach offers a quantitative way of sizing temperature levels in each DH system according to the listed methodology and the designer's preference.

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Impact of Domestic Hot Water Systems on District Heating Temperatures

Energies ◽

10.3390/en12244694 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4694

Author(s):

Tina Lidberg ◽

Thomas Olofsson ◽

Louise Ödlund

Keyword(s):

Low Temperature ◽

District Heating ◽

Heating System ◽

Hot Water ◽

Space Heating ◽

Circulation System ◽

District Heating System ◽

Domestic Hot Water ◽

Temperature Levels ◽

The Impact

When buildings become more energy effective, the temperature levels of district heating systems need to be lower to decrease the losses from the distribution system and to keep district heating a competitive alternative on the heating market. For this reason, buildings that are refurbished need to be adapted to suit low-temperature district heating. The aim of this paper is to examine whether four different energy refurbishment packages (ERPs) can be used for lowering the temperature need of a multi-family buildings space heating and domestic hot water (DHW) system as well as to analyse the impact of the DHW circulation system on the return temperature. The results show that for all ERPs examined in this study, the space heating supply temperature agreed well with the temperature levels of a low-temperature district heating system. The results show that the temperature need of the DHW system will determine the supply temperature of the district heating system. In addition, the amount of days with heating demand decreases for all ERPs, which further increases the influence of the DHW system on the district heating system. In conclusion, the DHW system needs to be improved to enable the temperature levels of a low-temperature district heating system.

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Natural gas heating in Serbian settlements according to urbanity parameters

Facta universitatis - series Architecture and Civil Engineering ◽

10.2298/fuace0801139b ◽

2008 ◽

Vol 6 (1) ◽

pp. 139-153 ◽

Cited By ~ 2

Author(s):

Dejan Brkic

Keyword(s):

Natural Gas ◽

Distribution System ◽

Optimal Solution ◽

District Heating ◽

Heating System ◽

Hot Water ◽

Gas Distribution ◽

District Heating System ◽

Energy Supply System ◽

Gas Heating

Natural gas can be directly used for heating of flats by gas distribution system. Indirectly, heating power plant can disburse natural gas and deliver hot water or steam for heating of flats. Decision of optimal way for gas heating usage is done based on spatial disposal of building, number and size of buildings in settlement, etc. Optimal solution, between gas distribution and district heating system (local or district heating by natural gas), can be done according to methodology (model approach) shown in this paper. According to variety of Serbian settlements (in density, size and layout of buildings) model which has ability to represent their different characteristics is formed. This model could be simple and useful tool for initial decision about energy supply system.

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Analysis and comparison of methods for the preparation of domestic hot water from district heating system, selected renewable and non-renewable sources in low-energy buildings

E3S Web of Conferences ◽

10.1051/e3sconf/20183003001 ◽

2018 ◽

Vol 30 ◽

pp. 03001

Author(s):

Maciej Knapik

Keyword(s):

Renewable Energy ◽

Energy Demand ◽

Renewable Energy Sources ◽

District Heating ◽

Heating System ◽

Hot Water ◽

Low Energy ◽

Energy Sources ◽

District Heating System ◽

Domestic Hot Water

The article presents an economic analysis and comparison of selected (district heating, natural gas, heat pump with renewable energy sources) methods for the preparation of domestic hot water in a building with low energy demand. In buildings of this type increased demand of energy for domestic hot water preparation in relation to the total energy demand can be observed. As a result, the proposed solutions allow to further lower energy demand by using the renewable energy sources. This article presents the results of numerical analysis and calculations performed mainly in MATLAB software, based on typical meteorological years. The results showed that system with heat pump and renewable energy sources Is comparable with district heating system.

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Experimental validation of a model-based method for separating the space heating and domestic hot water components from smart-meter consumption data

E3S Web of Conferences ◽

10.1051/e3sconf/202017212001 ◽

2020 ◽

Vol 172 ◽

pp. 12001 ◽

Cited By ~ 1

Author(s):

Rasmus Elbæk Hedegaard ◽

Martin Heine Kristensen ◽

Steffen Petersen

Keyword(s):

Residential Buildings ◽

District Heating ◽

Energy Performance ◽

Hot Water ◽

Space Heating ◽

Smart Meter ◽

Smart Meters ◽

Ground Truth Data ◽

Domestic Hot Water ◽

Model Based

Smart meters are currently being rolled out in European district heating (DH) systems at a large scale to enable time-varying district heating tariffs and improve consumer awareness about their own consumption. Smart-meter data can also be used in more advanced applications, e.g. for establishing model-based control schemes for demand response purposes and data-driven building energy performance labeling schemes. Many of these applications require separate measurements of the consumption for space heating (SH) and preparation of domestic hot water (DHW); however, smart meters often only provide the total DH energy consumption (SH+DHW) in truncated units (e.g. whole kWh on an hourly basis). Typical approaches for separating these two components of DH consumption require measurements with a high temporal and numerical resolution and are therefore not applicable to smart-meter data. New methods suitable for disaggregating the combined DH demand are therefore needed. This paper presents a validation of a model-based method for disaggregating DH consumption using ground truth data from 44 residential buildings.

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Natural gas heating in Serbian settlements according to urbanity parameters

10.31219/osf.io/pf6cb ◽

2017 ◽

Author(s):

Dejan Brkić

Keyword(s):

Natural Gas ◽

Distribution System ◽

Optimal Solution ◽

District Heating ◽

Heating System ◽

Hot Water ◽

Gas Distribution ◽

District Heating System ◽

Energy Supply System ◽

Gas Heating

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Real Domestic Hot Water Consumption in Residential Buildings and Its Impact on Buildings’ Energy Performance—Case Study in Poland

Energies ◽

10.3390/en14165010 ◽

2021 ◽

Vol 14 (16) ◽

pp. 5010

Author(s):

Katarzyna Ratajczak ◽

Katarzyna Michalak ◽

Michał Narojczyk ◽

Łukasz Amanowicz

Keyword(s):

Energy Consumption ◽

Natural Gas ◽

Water Consumption ◽

Residential Buildings ◽

Energy Performance ◽

Primary Energy ◽

Hot Water ◽

Domestic Hot Water ◽

Total Energy Balance ◽

Consumption Rates

A building’s energy consumption is assessed considering the energy required for heating, cooling, lighting, and domestic hot water (DHW). Methodologies used to calculate energy certificates in European Union countries consider hot water consumption rates per person or per heated (floor) area, giving wide-ranging values (35–88 dm3/person/day). Using extreme parameters, it is possible to obtain a primary energy index that meets the legal requirements, although unrealistically large proportions of domestic hot water use relative to the total energy balance of the building may marginalize the influence of other components, such as fluctuations in heating, ventilation, or lighting. In the current work, the DHW consumption of three residential buildings was measured to verify the energy consumption for hot water preparation. Investigations were conducted based on the consumption of natural gas for DHW preparation. Experimentally obtained water consumption rates were determined per m2 of a dwelling and per person living in the building. The calculated indicators (0.85 ± 0.005 dm3/m2/day and 27.4 ± 1.4 dm3/person/day) were lower than those used for energy certifications of buildings. The experimentally obtained indicators were used in further theoretical energy assessments of six residential buildings. By adopting the designated indicators, the analyzed buildings met the legally required primary energy value (<70 kWh/m2/year) when using natural gas as a heat source. Applying more realistic DHW consumption values resulted in more accurate energy certifications.

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Analysis of the Methodology to Obtain Several Key Indicators Performance (KIP), by Energy Retrofitting of the Actual Building to the District Heating Fuelled by Biomass, Focusing on nZEB Goal: Case of Study

Energies ◽

10.3390/en12010093 ◽

2018 ◽

Vol 12 (1) ◽

pp. 93 ◽

Cited By ~ 3

Author(s):

Rosaura Castrillón Mendoza ◽

Javier Rey Hernández ◽

Eloy Velasco Gómez ◽

Julio San José Alonso ◽

Francisco Rey Martínez

Keyword(s):

Energy Efficiency ◽

Natural Gas ◽

Energy Management ◽

District Heating ◽

Heating System ◽

Energy System ◽

Hot Water ◽

The European Union ◽

District Heating System ◽

The University

In order to achieve the objectives of the European 20/20/20 strategy, and to obtain a greater energy efficiency, integration of renewable energies and the reduction of carbon emissions, a District Heating (DH) system has been designed by the University of Valladolid (UVa), Spain, one of the most important DH fed by biomass fuel in Spain, supplying heating and domestic hot water (DHW) to 31 buildings in Valladolid, the majority of them, educational buildings on the University Campus. The aims of this paper were to study the change from an energy system fueled by natural gas to District Heating by biomass in a building on the campus of the University of Valladolid—the School of Engineering (EII)—studying its consumption from its connection to the District Heating system. An energy management methodology such as ISO 50001 is carried out, applied to efficiency systems in buildings, thus establishing new criteria of sustainability and economic value. In this paper, energy management will also be analyzed in accordance with the proposed tools of an Energy Management System (EMS) applied to the EII building, through the measurement of energy parameters, calculation of thermal consumption, thermal energy savings as a result of the change from system to District Heating by biomass, economic savings, reduction of environmental impact and indicators of thermal efficiency I100 and CUSUM indicator. Finally, the primary renewable and non-renewable energy efficiency indicators for the new District Heating system will be determined. The concept of the near Zero Energy Buildings is defined in the European Union (EU) in order to analyze an approach to an nZEB which results from replacing the natural gas heating system by a biomass District Heating system.

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THE USE OF SOLAR ENERGY FOR PREPARING DOMESTIC HOT WATER IN A MULTI-STOREY BUILDING / SAULĖS ENERGIJOS PANAUDOJIMAS KARŠTAM VANDENIUI RUOŠTI DAUGIABUČIAME NAME

Mokslas - Lietuvos ateitis ◽

10.3846/mla.2012.81 ◽

2012 ◽

Vol 5 (4) ◽

pp. 507-512 ◽

Cited By ~ 3

Author(s):

Giedrius Šiupšinskas ◽

Solveiga Adomėnaitė

Keyword(s):

Flat Plate ◽

Water System ◽

District Heating ◽

Heating System ◽

Hot Water ◽

Solar Collectors ◽

District Heating System ◽

Climate Conditions ◽

Domestic Hot Water ◽

Life Project

The article analyses the possibilities of solar collectors used for a domestic hot water system and installed on the roofs of modernized multi-storey buildings under the existing climate conditions. A number of combinations of flat plate and vacuum solar collectors with accumulation tank systems of various sizes have been examined. Heat from the district heating system is used as an additional heat source for preparing domestic hot water. The paper compares calculation results of energy and economy regarding the combinations of flat plate and vacuum solar collectors and the size of the accumulation tank. The influence of variations in the main indicators on the final economic results has also been evaluated. Research has been supported applying EC FP7 CONCERTO program (‘‘Sustainable Zero Carbon ECO-Town Developments Improving Quality of Life across EU - ECO-Life’’ (ECO-Life Project) Contract No. TREN/FP7EN/239497/”ECOLIFE”). Santrauka Straipsnyje analizuojamos saulės kolektorių, skirtų karšto vandentiekio sistemai ant modernizuojamų daugiabučių namų stogų įrengti esamomis klimatinėmis sąlygomis galimybės. Nagrinėjamos įvairaus dydžio plokščiųjų ir vakuuminių saulės kolektorių su akumuliacinėmis talpyklomis sistemų kombinacijos. Kaip papildomas šilumos šaltinis karštam vandeniui pašildyti naudojama iš centralizuotų šilumos tinklų tiekiama šiluma. Lyginami plokščiųjų, vakuuminių saulės kolektorių ir akumuliacinio bako dydžio kombinacijų energinių ir ekonominių skaičiavimų rezultatai. Įvertinama kai kurių esminių rodiklių pokyčių įtaka galutiniams ekonominiams rodikliams.

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