Integrating Low-temperature Heating Systems into Energy Efficient Buildings

Abstract

Energy requirements for space heating and domestic hot water supplies in the Swedish building sector are responsible for almost 60 % of the total energy used. To decrease this enormous figure, energy saving measures are required, as well as opportunities to use low-temperature heating systems for increase sustainability. The present paper studies low-temperature heating systems, including heat production units (district heating or heat pumps) and heat emitting units in the room. The aim was to find an answer to the question of whether or not low-temperature heating systems are energy efficient and sustainable compared with conventional heating systems. To answer this question, we considered different efficiency aspects related to energy and exergy. The analysis showed that low-temperature heating systems are more energy efficient and environmentally friendly than conventional heating systems. This was attributed to heat pumps and district heating systems with lower temperature heat emitters using a greater share of renewable resources and less auxiliary fuels. This report discusses the pros and cons of different types of low-temperature heat emitters.<p>QC 20150812. QC 20160411</p

Are typical radiators over-dimensioned? An analysis of radiator dimensions in 1645 Danish houses

“…The distribution of observations across the various periods is shown in Fig. 1 (left) and was found to correspond well with the average distribution of single-family houses in Denmark, where a large number of houses were built during a building boom in 1960-1980 (groups [5][6] and in the period 1900-1950 (included in groups 2-3). The geographical grouping was based on six geographical areas in Denmark (Greater Copenhagen, Zealand, Funen, Southern Jutland, Mid Jutland, and Northern Jutland), as shown in Fig.…”

“…For example, Ploskid and Holmberg [2] have shown that operating a heating system with supply and return temperatures of 40 °C/30 °C instead of 55 °C/45 °C can improve heat pump efficiency by up to 25% and thus reduce CO 2 emissions from heating by up to 24%. In a review, Ovchinnikov et al [3] report additional benefits from low-temperature heating, including reduced heat losses from distribution systems in multi-family buildings [4] and improved thermal comfort [5].…”

Impact of Domestic Hot Water Systems on District Heating Temperatures

“…Future district heating systems may have significantly lower supply and return temperatures than today's systems, and several studies have been made in this area which are often referred to as the fourth generation of district heating systems [8][9][10][11]. For buildings using heat pumps for space heating and domestic hot water (DHW), lowering the heat system temperatures is an effective way to increase the heat pump efficiency and thereby also decrease the levels of carbon dioxide emissions due to decreased electricity use [12,13].…”

Novel Energy System Design Workflow for Zero-Carbon Energy District Development

“…Low-temperature heating is crucial for lowering energy loss and improving systems energy and exergy efficiencies. Heating supply temperatures as low as 30 and 35 • C are shown to be feasible for surface heating and fan coil systems (Hesaraki et al, 2015). Furthermore, many studies have shown that a supply temperature of 40 • C is sufficient for meeting the domestic hot water demand.…”