A district heating system
(less commonly called
) is a system for distributing heat
generated in a centralized location for residential and commercial
heating requirements such as space
and water heating
heat is often obtained from a cogeneration
plant burning fossil fuels but
, although heat-only boiler stations
, geothermal heating
and central solar heating
are also used,
as well as nuclear power
heating plants can provide higher efficiencies and better pollution
control than localized boilers. According to some research,
District Heating with Combined Heat and Power - CHPDH is the
cheapest method of cutting carbon, and has one of the lowest carbon
footprints of all fossil generation plants.
The core element of a district heating system is usually a cogeneration
plant (also called combined heat and power
, CHP) or a
heat-only boiler station
Both have in common that they are typically based on combustion of
primary energy carriers. The difference between the two systems is
that, in a cogeneration plant, heat and electricity are generated
simultaneously, whereas in heat-only boiler stations - as the name
suggests - only heat is generated.
The combination of cogeneration and district heating is very
. A thermal power station
only electricity can convert less than approximately 50 % of
the fuel input into electricity. The major part of the energy is
wasted in form of heat and dissipated to the environment. A
cogeneration plant recovers that heat and can reach total energy
efficiency beyond 90 %.
Other heat sources for district heating systems can be geothermal
heat, solar heat, surplus heat from industrial processes, and
Nuclear energy can be used for district heating. The principles for
a conventional combination of cogeneration and district heating
applies the same for nuclear as it does for a thermal power station
. One use of nuclear
heat generation was with the Ågesta Nuclear
Power Plant in Sweden. In Switzerland, the Beznau Nuclear
Power Plant provides heat to about 20,000 people.
has several cogeneration nuclear plants which together provided
11.4 PJ of district heat in 2005. Russian nuclear district heating
is planned to nearly triple within a decade as new plants are
District heating pipe in Tübingen, Germany
After generation, the heat is distributed to the customer via a
network of insulated pipes
heating systems consists of feed and return lines. Usually the
pipes are installed underground but there are also systems with
overground pipes. Within the system heat storage
may be installed to even
out peak load demands.
The common medium used for heat distribution is water, but also
is used. The advantage of steam is that
in addition to heating purposes it can be used in industrial processes
due to its higher
temperature. The disadvantage of steam is a higher heat loss due to
the high temperature. Also, the thermal efficiency
of cogeneration plants
is significantly lower if the cooling medium is high temperature
steam, causing smaller electric power
generation. Heat transfer oils are generally not used for district
heating, although they have higher heat capacities than water, as
they are expensive, and have environmental issues.
At customer level the heat network is connected to the central heating
of the dwellings by heat exchangers
(heat substations). The water
(or the steam) used in the district heating system is not mixed
with the water of the central heating system of the dwelling.
Typical annual loss of thermal energy through distribution is
around 10%, as seen in Norway's district heating network.
Pros and cons
District heating has various advantages compared to individual
heating systems. Usually district heating is more energy efficient,
due to simultaneous production of heat and electricity in combined
heat and power generation plants. The larger combustion units also
have a more advanced flue gas
single boiler systems. In the case of surplus heat from industries,
district heating systems do not use additional fuel because they
use heat (termed heat recovery) which would be disbursed to the
District heating is a long-term commitment that fits poorly with a
focus on short-term returns on investment. Benefits to the
community include avoided costs of energy, through the use of
surplus and wasted heat energy, and reduced investment in
individual household or building heating equipment. District
heating networks, heat-only boiler stations, and cogeneration
plants require high initial capital expenditure and financing. Only
if considered as long-term investments will these translate into
profitable operations for the owners of district heating systems,
or combined heat and power plant operators. District heating is
less attractive for areas with low population densities, as the
investment per household is considerably higher. Also it is less
attractive in areas of many small buildings; e.g. detached houses
than in areas with a few much larger buildings; e.g. blocks of
flats, because each connection to a single-family house is quite
Carbon footprint & cost of reduction
One study shows that District Heating with Combined Heat and Power
has the lowest carbon footprint of any heating system, and it
rapidly competes with extra insulation.
Since conditions from city to city differ, every district heating
system is uniquely constructed. In addition, nations have different
access to primary energy carriers and so they have a different
approach how to address the heating market within their
borders.This leads not only to a different degree of diffusion but
also to different district heating systems in general throughout
Since 1954, district heating has been promoted in Europe
by Euroheat & Power. They have compiled an
analysis of district heating and cooling markets in Europe within their Ecoheatcool project supported by the European
The legal framework in the member states of
the European Union
influenced by the EU-CHP
largest district heating system in Austria is in
Vienna (Fernwärme Wien) - with many smaller systems
distributed over the whole country.
District heating in Vienna is run by Wien
. In the business year of 2004/2005 a total of
5.163 GWh was sold, 1.602 GWh to 251.224 private
apartments and houses and 3.561 GWh to 5211 major
The three large municipal waste incinerators
provide 22 % of the total in
producing 116 GWh electric power and 1.220 GWh heat.
Waste heat from municipal power plants and large industrial plants
account for 72 % of the total. The remaining 6 % is
produced by peak heating boilers from fossil fuel.
Denmark, district heating covers more than 60% of space heating and water heating.
In 2007, 80.5% of this
heat was produced on combined
heat and power
plants. Heat recovered from waste incineration
accounted for 20.4% of the
total Danish district heat production. Most major cities in Denmark
have big district heating networks including transmission networks
operation with up to 125°C and 25 bar pressure and distribution
networks operating with up to 95°C and between 6 and 10 bar
pressure. The largest district heating system in
Denmark is in the Copenhagen area operated by CTR I/S and VEKS I/S.
In central Copenhagen, the CTR
network serves 275,000 households (90-95% of the area's population)
through one network of 54-kilometer double district heating
distribution pipes providing a peak capacity of 663 MW. The
consumer price of heat from CTR is approximately €49 per MWh
plus taxes (2009).
In Finland district heating accounts for about 50 per cent of the
total heating market , 4/5 of which being produced from combined heat and power
90 per cent of apartment blocks, more than half of all terraced
houses, and the bulk of public buildings and business premises are
connected to a district heating network. Natural Gas
is mostly used in areas to the south
east gas pipeline network, imported coal
used in areas close to ports, and peat
in northern areas where peat is a natural resource. However, other
renewables such as wood chips and other paper industry combustible
by-products are also used, as is the energy recovered by the
of municipal solid waste
units which generate heat as an industrial by-product may sell
otherwise waste heat to the network rather than release it to the
environment. In some towns, waste incineration can contribute as
much as 8% of the district heating heat requirement. Availability
is 99.98% and disruptions when
they do occur usually reduce temperatures by only a few
Germany district heating has a market share of around
14 % in the residential buildings sector.
heat load is around 52.729 MW. The heat comes mainly from
cogeneration plants (83 %). Heat-only boilers supply 16 %
and 1 % is surplus heat from industry. The cogeneration plants
use natural gas (42 %), coal (39 %), lignite (12 %)
and waste/others (7 %) as fuel.
largest district heating network is located in Berlin whereas the
highest diffusion of district heating occurs in Flensburg with around 90% market share.
District heating has rather little legal framework in Germany.
There is no law on it as most elements of district heating are
regulated in governmental or regional orders. There is no
governmental support for district heating networks but a law to
support cogeneration plants. As in the European Union the CHP Directive
will come effective, this law
probably needs some adjustment.
of all housing (mostly in the capital of Reykjavik) enjoying district heating services - mainly from
geothermal energy, Iceland is the
country with the highest penetration of district
Most of the district heating in Iceland comes from three main
geothermal power plants, producing over 800 MWth:
- Svartsengi combined heat and power plant (CHP)
- Nesjavellir CHP plant
- Hellisheidi CHP plant
Italy, district heating is used in some cities (Bergamo, Brescia, Bolzano, Ferrara, Reggio
Emilia, Terlan, Torino).
heating only constitutes approx.
2 % of energy needs for
heating. This is a very low number compared to similar countries.
One of the main reasons district heating has a low penetration in
Norway is access to cheap hydro based electricity. However, there
is district heating in the major cities.
Russian cities, district-level combined heat and power plants ( )
produce more than 50 % of the nation's electricity and
simultaneously provide hot water for neighbouring city
They mostly use coal
for cogeneration of heat. Now, gas turbines
and combined cycle
designs are beginning to be
widely used as well. A Soviet-era approach
of using very large central stations to heat large districts of a
big city or entire small cities is fading away as due to
inefficiency, much heat is lost in the piping network because of
leakages and lack of proper thermal insulation .
heating was used throughout the main cities, particularly in the
capital, Belgrade. NATO targeted one
of the main DH plants, the District Heating Plant of New Belgrade
(JKP "Beogradske elektrane") during the Kosovo
.This plant was deemed the beginning of the
centralized heating supply to Belgrade, built in 1961 as a means to
provide effective heating to the newly built suburbs of Novi Beograd.
The district heating system of Belgrade
possesses 112 heat sources of 2,454 MW capacity and by way of
the pipelines more than 500 km long and 4365 connection
stations, providing district heating to 240,000 apartments and
7,500 office/commercial buildings of the total floor area exceeding
17,000,000 square meters.
Sweden has a long
tradition for using district heating in urban
areas.The city of Växjö has reduced
its fossil fuel consumption by 30% in 1993-2006 and aims at 50%
reduction in 2010.
This is to a large extent to be achieved
by way of biomass fired district heating
90% of the energy in Swedish district heating system are usually
produced with renewable sources. The remaining 10 % are only used
when the weather is really cold and there is a very high energy
demand. Because of the law forbidding landfill, waste is commonly
used as a fuel.
Kingdom, district heating also became popular after
World War II, but on a restricted
scale, to heat the large residential estates that replaced areas
devastated by the Blitz.
(right) shows the accumulator at the Pimlico District Heating
Undertaking (PDHU), just north of the River
. The PDHU first became operational in 1950 and continued
to expand up till about 1960. The PDHU once relied on waste heat from the
now-disused Battersea Power Station on the South side of the River Thames.
It is still in operation,
the water now being heated locally by a new energy centre which
incorporates 3.1 MWe /4.0 MWTh of CHP engines and 3 x
8 MW gas fired boilers.
the United Kingdom's largest district heating schemes is
EnviroEnergy in Nottingham. Plant initially built by Boots is now used to heat 4,600 homes, and a
wide variety of business premises, including the Concert
Hall, the Nottingham Arena, the Victoria Baths, the Broadmarsh
Shopping Centre, the Victoria Centre and others.
The heat source is a Waste-to-energy
Scotland has several district heating systems with the first in the
UK being installed at Aviemore and others following at
Lochgilphead, Fort William and Forfar.
Many other such heating plants still operate on estates across
Britain. Though they are said to be efficient, a frequent complaint
of residents is that the heating levels are often set too high -
the original designs did not allow for individual users to have
their own thermostats
In North America
, district heating
systems fall into two general categories. Those that are owned by
and serve the buildings of a single entity are considered
institutional systems. All others fall into the commercial
District Heating is becoming a growing industry in Canadian cities,
with many new systems being built in the last ten years. Some of
the major systems in Canada include:
- Montreal, QC has a district heating and cooling system in the
- Toronto, ON - Enwave
provides district heating and cooling within the downtown core of
Toronto, including deep lake cooling technology, which
circulates cold water from Lake Ontario through heat exchangers to
provide cooling for many buildings in the city.
- Calgary, AB: ENMAX is currently building
its Calgary Downtown District Energy Centre which will provide
heating to up to 10 million square feet of new and existing
residential and commercial buildings. Construction of the Calgary Downtown District Energy Centre has
begun with commercial operation anticipated for March 2010.
- Vancouver, BC:
- Central Heat Distribution
Ltd. operates a central heating plant in the downtown core of
Columbia. In addition to building heating, the Central
Heat Distribution network also drives a steam clock.
- A large scale district heating system is currently being
constructed in South East False Creek in the downtown Vancouver
core that will serve may new developments being constructed,
including the 2010 Olympic Village. A large portion of the heating
demand for this system will come from an innovative sewer heat
recovery system, which will greatly reduce greenhouse gas
- Windsor, ON has a district heating and cooling system in the
- Drake Landing, AB, is small in size (52 homes) but notable for
having the only central solar
heating system in North America.
Many Canadian universities operate central campus heating
Consolidated Edison of New York (Con Ed) operates the New York City steam system, the
largest commercial district heating system in the world.
system has operated continuously since March 1882 and serves
Island from the Battery through 96th Street.
operating smoothly for most of its time in service, incidents have
occurred, On July 18
, one person was killed and numerous others injured
when a steam pipe
on 41st Street and Lexington. In 1989 also, three
people were killed in a similar event. In addition to providing
space and water heating, steam from the system is used in numerous
restaurants for food preparation, process heat in laundries and dry
cleaners, as well as to power absorption chillers
for air conditioning
. NRG Energy also operates district systems in
major cities of San
Francisco, Harrisburg, Minneapolis, Pittsburgh and San
operates a district system in Seattle.
Detroit Edison operates a district system in
Detroit that started operation at the Willis
Avenue Station in 1903.
heating is also used on many college campuses most notably the
of Notre Dame which produces over half its own electricity and
all of its heating needs from the same plant.
district heating enterprises are operating in Japan, serving
Many companies operate district cogeneration facilities that
provide steam and/or hot water to many of the office buildings.
most operators in the Greater Tokyo serve district cooling.
District heating traces its roots to the hot water-heated baths and
greenhouses of the ancient Roman
. District systems gained prominence in Europe
during the Middle
, with one
system in France in continuous operation since the 14th century.
U.S. Naval Academy in Annapolis began steam district heating
service in 1853.
these and numerous other systems have operated over the centuries,
the first commercially successful district heating system was
launched in Lockport, New York, in 1877 by American hydraulic engineer Birdsill Holly, considered the founder of
modern district heating.
Paris has been
using geothermal heating from a
55-70 °C source 1–2 km below the surface since the 1970s
for domestic heating.
1980s Southampton began utilising combined heat and power district
heating, taking advantage of geothermal heat "trapped" in the
The geothermal heat provided by the well works in
conjunction with the Combined Heat and Power scheme. Geothermal
energy provides 15-20 %, fuel oil
10 %, and natural gas
70 % of
the total heat input for this scheme and the combined heat and
power generators use conventional fuels to make electricity. "Waste
heat" from this process is recovered for distribution through the
11 km mains network.
The future of many of these systems are in doubt. The same kind of
problems many district heating operations in former Soviet Union
and Eastern Europe have today, many North American steam district
heating systems began to experience in the 1960s and 1970s. In
North America, the owners (in many cases power utilities) lost
interest in the district heating business and provided insufficient
funding for maintenance, and the systems and service to customers
started to deteriorate. The result was that the systems started
losing customers. The reliability decreased and finally the whole
system closed down. For example, in Minnesota in the 1950s there
were about 40 district steam systems, but today only a few
Market penetration of district heating
Penetration of district heating (DH) into the heat market varies by
country. Penetration is influenced by different factors, including
environmental conditions, availability of heat sources and economic
and legal framework.
In the year 2000 the percentage of houses supplied by district heat
in some European countries was as follows:
In Iceland the prevailing positive influence on DH is availability
of easily captured geothermal heat
In most East European countries energy planning included
development of cogeneration
district heating. Negative influence in The Netherlands and
UK can be attributed partially to milder climate and
also competition from natural gas
According to Helsingin Energia, consumption of energy by district
heating in Helsinki since 1970 peaked in 1971, at
67 kWh/m³/year, falling to 43 kWh/m³/year in 1997, since
when it has not fluctuated greatly.
Figures for Sweden suggest that the average Swede using district
heating receives 4500 kWh/year from the system.
The opposite of district heating is district cooling
. Working on broadly
similar principles to district heating, district cooling delivers
chilled water to buildings like offices and factories needing
cooling. In winter, the source for the cooling can often be sea
water, so it is a cheaper resource than using electricity to run
compressors for cooling.
The Helsinki district cooling system uses otherwise wasted heat
from summer time CHP power generation units to run absorption refrigerators
during summer time, greatly reducing electricity usage. In winter
time, cooling is achieved more directly using sea water. The
adoption of district cooling is estimated to reduce the consumption
of electricity for cooling purposes by as much as 90 per cent and
an exponential growth in usage is forecast. The idea is now being
adopted in other Finnish cities. The use of district cooling grow
also rapidly in Sweden in a similar way.
University's Lake Source Cooling System uses Cayuga Lake as a heat sink to operate the central chilled water
system for its campus and to also provide cooling to the Ithaca
City School District.
The system has operated since the
summer of 2000 and was built at a cost of $55–60 million. It cools
a 14,500 tons
2004, Enwave Energy Corporation, a district energy company based in
Toronto, Canada, started
operating system that uses water from Lake Ontario to cool downtown buildings, including office
towers, the Metro Toronto Convention Centre, a small brewery and a
The process has become known as
Deep Lake Water Cooling
(DLWC). It will provide for over 40,000 tons
) of cooling—a significantly larger system
than has been installed elsewhere. Another feature of the Enwave
system is that it is integrated with Toronto’s drinking water
supply. The Toronto drinking water supply required a new intake
location that would be further from shore and deeper in the lake.
This posed two problems for the utility that managed the city's
drinking water supply: 1. the capital cost of moving the water
intake location and additionally, the new location would supply
water that was so cold it would require heating before it could be
distributed. The cooperation of the district cooling agency,
Enwave, solved both problems: Enwave paid for the cost of moving
the water intake and woudl also supply the heat to warm the
drinking water supply to acceptable levels by effectively
extracting the heat from the buildings served by Enwave. Contact
between drinking water and the Enwave cooling system is restricted
to thermal contact in a heat exchanger. Drinking does not circulate
through the Enwave cooling systems.
In January 2006, PAL technology is one of the emerging project
management companies in UAE involved in the diversified business of
desalination plant, sewerage plant to district cooling system. More
than 400,000 Tons of district cooling projects are already in the
pipe line whilst negotiating other key projects in the
In 2006, a district cooling system came online in Amsterdam's
Zuidas, drawing water from the Nieuwe Meer
- SUGIYAMA KEN'ICHIRO (Hokkaido Univ.) et al. Nuclear District Heating: The Swiss
- Nuclear Power in Russia
Norwegian Water Resources and Energy Directorate
- Kort om elforsyning i Danmark, from the
Homepage of Dansk Energi (in Danish).
- Danish Energy Statistics 2007 by the Danish
Ministry of Energy (in Danish).
- Environmentally Friendly District Heating to Greater
Copenhagen, publication by CTR I/S (2006)
- Prisen på Fjernvarme, price list from the
Danish homepage of a Copenhagen district heating provider Københavns Energi
- District heating in Finland
- AGFW Branchenreport 2006, by the German Heat
and Power Association -AGFW- (in German).
- Би-би-си | Россия | В Сибири и Якутии ждут подачи
- Fossil Fuel Free Växjö from the homepage of the
Municipality of Växjö
- 平成21年4月現在支部別熱供給事業者: The Japan Heat Service Utilities
- 080304 bbm.me.uk
- 080304 energie-cites.org
- Sabine Froning (Euroheat & Power): DHC/CHP/RES
a smile for the environment, Kiev 2003
- Figures supplied by email to Alaric Hall, 28.5.2007.
- Chris Goodall, How to Live a Low-Carbon
Life: The Individual's Guide to Stopping Climate Change
(London: Earthscan, 2007), p. 85.
- Lake water air conditioning cuts CO2 emissions by
70% compared to conventional cooling
- District cooling in Amsterdam's Zuidas