ENERGY MANAGEMENT
District heang networks are becoming an increasingly important part of the government’s plan to reduce carbon emissions and cut heang bills for
homeowners. With the future of tradional fossil fuel heang systems becoming uncertain, the focus has shied to the development of innovave and ecient heat networks. With that in mind, Steve Richmond of REHAU’s Building Soluons’ division, explores what steps companies are taking to drive the new generaon of district heang soluons
uAs well as reducing heat losses across the network, fourth generaon district heang systems have been designed with a low carbon heat source in mind
innovation within this sector has therefore shifted towards the development of heating systems that run more efficiently, can reduce energy bills and crucially, reduce carbon emissions.
F Moving to the fourth generation
District heating systems supply buildings with heating and hot water from a large centralised heat source, which is connected to buildings via an underground network of buried pre-insulated pipes. This set-up supplies multiple buildings in a network, reducing the carbon emissions per building in addition to the cost and time that maintenance of individual boilers incurs. The majority of district heating systems currently being implemented in Europe are of the third generation, where the water in circulation is at 70- 95˚C flow temperature. However, the transition to the new fourth generation of district heating system has begun. Within this new generation, the water circulates at 40-60˚C, meaning less heat is being lost or wasted within the network, as they are designed to meet the demands of energy consumers in a more efficient manner. Reduction in heat loss due to the lower flow temperatures, smaller pipe sizes, and the resulting reduced capital and operational costs have made fourth generation technology an attractive proposition for key developers. The lower costs of installation and maintenance associated with this system also make reducing customer bills a viable goal for housing associations and the public sector. As well as reducing heat losses across the network, fourth generation district heating systems have been designed with a low carbon heat source in mind. Centralised air, water or ground source heat pumps are ideally suited to the lower temperatures allowed by fourth generation district heating systems. This significantly reduces the carbon emissions compared to gas-powered heat networks and, therefore, poses a significant reduction in emissions that highlights district heating’s status as an efficient and sustainable heating system for the future.
Driving down carbon
The transition to district heating systems is now more pressing than ever due to recent investigations by the Committee for Climate Change (CCC). Published in February 2019, the committee’s report included proposals for improving energy efficiency and reducing carbon emissions across the heating market. The CCC’s report has driven government policy to achieving a net zero rate of carbon emissions across the UK by 2050, and furthermore led to the establishment of the Future Homes Standard for
inite supplies of fossil fuels and a greater awareness of climate change have made fossil fuel boilers a less attractive option when it comes to heating our buildings going forwards. The focus of
BSEE District heating is the future
2025, which bans the installation of fossil fuel boilers in new build homes. With district heating being the favoured alternative, developers must carefully consider flow temperatures within the network. This is especially the case considering that the CIBSE / ADE CP1 – the code of practice setting out minimum requirements for a heat network – recommends a maximum flow temperature of 70˚C in new systems. Heat pumps are even more of an attractive proposition following the new lower emissions factor for electricity detailed in the tenth version of the Standard Assessment Procedure for building regulations (SAP10), which is out for consultation and comes into effect in 2020. It denotes a value of 0.233kg CO2/kWH should be adhered to as opposed to the value 0.519 outlined in the current SAP 2012. Since then the Draft SAP 10.1 consultation published on 1 October 2019 has put forward a yet lower value of 0.136, a 75 per cent improvement in carbon savings of electricity used by a heat pump from the original SAP 2012 figures. This swift trend in decarbonisation of the grid is paving the way for low carbon heat pumps.
Furthermore, the Heat Networks Investment Project (HNIP) have in their scoring of projects applying for grants or loans encouraged projects that use commercial-scale heat pumps and very low or ambient temperature distribution systems.
The polymer solution
With carbon and cost reductions the driving factors behind the transition to district heating, interest in modern efficient heat networks, particularly those that use polymer pipework, is now higher than ever. To meet the demand of the consumers, government bodies and developers, companies such as REHAU are producing district heating solutions that efficiently provide space heating and hot water while lowering emissions and reducing heating bills.
Despite their relatively new involvement in district heating networks, many studies and government reports have included the fact that polymer pipes have typically lower installation costs than traditional materials.
Corrosion associated with traditional steel pipework, which in some cases results in system failure and costly repair work, is minimised using polymer pipes. By contrast, the reduced flow temperatures of a fourth-generation network allow for polymer pipes with a lifespan well in excess of 50 years. With no welding involved in connecting the pipework, installation is quick and easy, and the flexibility of polymer solutions allows developers and contractors freedom throughout the design process and on-site during installation. REHAU’s pre-insulated PE-Xa pipework systems RAUVITHERM and RAUTHERMEX offer a reliable and proven solution suitable for district heating
Read the latest at:
www.bsee.co.uk
networks. RAUVITHERM’s combination of flexibility and low heat losses makes it an ideal choice for small-medium size heat networks or house connections off a main spine. RAUTHERMEX uses a high-performance polyurethane foam, making it an ideal option for a large district heating network. The insulation afforded by the polyurethane rigid (PUR) foam ensures minimal heat losses across the network, further enhancing system efficiency.
Alongside fourth generation networks, there are also fifth generation heat networks, which use flow temperatures of around 10-30˚C, a much lower temperature than 40-60˚C of the fourth- generation system. The heat sources on a fifth-generation network are often heat pumps where the heat is boosted by individual heat pumps in each building. One of the benefits is reduced heat losses in the network itself, but individual heat pumps are typically needed rather than one centralised heat pump on a fourth- generation network.
Developers, specifiers and contractors use polymer systems such as those from REHAU as the district heating market is rapidly changing from higher temperature traditional fossil fuel heat networks to lower temperature renewable heat networks. With the drive to reduce carbon, district heating is becoming a more widespread option to heat our homes and buildings efficiently.
www.rehau.uk/districtheating BUILDING SERVICES & ENVIRONMENTAL ENGINEER NOVEMBER 2019 23
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51
