Dimensioning of Solar Thermal Systems for Multi-Family Buildings in Lithuania: an Optimisation Study

Rokas Valancius,Juozas Vaičiūnas,Eugenijus Perednis,Andrius Jurelionis

doi:10.5755/j01.sace.11.2.12459

Abstract

Small-scale solar thermal domestic hot water (DHW) systems in Lithuania can produce up to 523 kWh per year per one square meter of solar collector area. It is therefore one of the most common solar thermal applications in the country with the expected payback period of approximately 10 years. However, the number of solar water heating systems (SWH) installed in the renovated multi-family buildings is quite limited. On the other hand, the potential of integrating solar thermal systems in these buildings is much higher as DHW usage during the day is more uniform in multi-family buildings compared to the single-family houses. This aspect brings out a higher solar energy share without adding additional volume to the hot water storage tank. Simplified optimization tools for solar collector area selection, volume selection for the accumulation tank, installation costs and payback period estimation are required for promoting SWH systems for DHW production in multi-family buildings. This paper deals with DHW consumption analysis in multi-family buildings in Lithuania as well as modelling of solar thermal systems to produce a tool for decision makers for preliminary analysis of SWH systems integration in renovated multi-family buildings. The main target group for the tool developed are multi-family buildings connected to district heating network. Simulation software “T*SOL 5.0 Pro” was used for SWH systems performance evaluation as well as financial analysis of SWH system alternatives.DOI: http://dx.doi.org/10.5755/j01.sace.11.2.12459

Highlights

The major part of thermal energy used in multi-family buildings in Lithuania are supplied via the district heating network. 72.4% from all district heating produced energy was used for household purposes in 2012 (LŠTA, 2013) and the price in different cities varies in the range from 0,458 EUR/ kWh to 0,901 EUR/kWh (LŠTA, 2015)
Simulations showed that SHW systems in Lithuania can reduce greenhouse gas (GHG) emissions from 92 to 147 kg CO2/m2absorber per year, when SHW systems efficiency varies from 35 to 55%
Analysis of domestic hot water consumption data showed that the average DHW demand for multi-family buildings in Lithuania is equal to 2.47 m3 per month

Summary

Introduction

The major part of thermal energy used in multi-family buildings in Lithuania are supplied via the district heating network. 72.4% from all district heating produced energy was used for household purposes in 2012 (LŠTA, 2013) and the price in different cities varies in the range from 0,458 EUR/ kWh to 0,901 EUR/kWh (LŠTA, 2015). The major part of thermal energy used in multi-family buildings in Lithuania are supplied via the district heating network. The multi-family building stock in Lithuania can contribute to reduction of both greenhouse gas (GHG) emissions and energy consumption of the country significantly by integrating medium-scale SWH systems under the framework of renovation initiatives. Relation between installation costs and area of the flat plate solar collectors (including heat storage tanks and auxiliary equipment) can vary in the range from 600 to 150 EUR/m2 in SHW from 10 m2 to 10000 m2. The installation costs, annual maintenance and repairs costs vary in wide range depending on type of solar collectors and other equipment as well, but in general, larger SWH installations are relatively cheaper to maintain than small-scale SWH systems (Andrews et al, 2012; Leutgöb and Rammerstorfer, 2013). In some cases installing SWH systems in existing buildings can cost up to 20% more than in new buildings

Objectives

Methods

Results

Conclusion