Heating and cooling constitutes around half of the EU's final energy consumption and is the biggest energy end-use segment, ahead of transport and electricity.
How heating and cooling for urban areas are supplied varies strongly from country to country and from city to city. Reasons for this variation are climatic conditions, locally available energy resources and strategic energy decisions in the past.
The technologies primarily used for heating purposes are oil and natural gas boilers. As can be seen in figure “European Final Energy Consumption by technology used for production”, around 70% of the heating consumption (3500 TWh/y) is covered by boilers: small boilers for residential and tertiary buildings cover 40% of the heat uses, while the remaining 30% is served through large gas boilers in industry and district heating networks. Electric space heaters and electric water heaters represent a significant even though minor share of the market with around 13% (about 650 TWh/y) of the thermal energy produced. Large fossil fuel driven CHP units produce a similar amount of heat in district heating systems.
The direct production of heat from thermal renewable energy sources is about 10% with the largest share (8.1%, 370 TWh/y) deriving from solid biomass crops.
Considering also the renewable electricity contribution, the renewable energy share for heating and cooling is only 15%.
This not only produces massive negative effects on:
which are high priorities on the EC agenda, but also results in:
If we consider single building gas boilers, the Primary Energy (PE) use (including gas transportation) is about 1.4 MWh per MWh of energy provided to the building (average thermal efficiency 80% and gas primary energy factor of 1.1, average European value from EUROSTAT are considered in this document) and the equivalent CO2 generated amounts to 320 kgCO2/MWh (eq. CO2 emission factor for gas 257 kgCO2/MWh).
Most DH networks in Europe are driven by means of fossil fuelled boilers and CHP units. Assuming the best large condensing gas boilers are installed with a thermal efficiency of 1 and an overall network efficiency of 80-85 %, PE of around 1.2 MWh is consumed for each MWh of energy provided to the network (corresponding to 260 kgCO2/MWh).
Large size gas driven cogenerators transforming around 85% of the final energy consumed into useful thermal energy (plus the above network efficiency), consume about 1.4 MWh of PE per MWh of energy made available to the network (corresponding to 310 kgCO2/MWh).
One can then assume roughly a PE use of 1.3 MWh and 300 kg of equivalent CO2 emissions per MWh of useful energy.
For heat production from electricity, a primary energy factor of 2.26 and eq. CO2 emission factor of 377 kg/MWh is assumed.
Crossing the environmental parameters with the above energy uses, we can calculate a huge consumption of PE in the range of 6000 TWh and 1.3 billion tons of equivalent CO2 a year.
Most air pollution is man-made and derives from combustion of fossil or biomass fuels (e.g. exhaust gasses from cars and fossil or wood boilers). In this sense, even though sustainable growth and harvested biomass is a renewable energy source, it cannot be considered as a long-term, sustainable energy source for urban areas.
In terms of pollutants local emissions the following parameters (average European) can be assumed with reference to individual gas boilers:
Once more these can be crossed with the fossil fuels consumption, leading to overall yearly pollutants emissions of about:
The calculation is conservative since the emissions from oil boilers are far larger.
Air pollution is the number one environmental cause of death in the EU, responsible for more than 400.000 premature deaths per year (EEA, 2016). According to WHO studies, exposure to particulate matter can cause or aggravate cardiovascular and lung diseases, heart attacks and arrhythmias, affect the central nervous system and the reproductive system and cause cancer.
Exposure to nitrogen dioxide increases symptoms of bronchitis in asthmatic children and reduces lung function growth.
Health-related external costs range from 330 billion to 940 billion euros per year, depending on the evaluation methodology (Europe, 2013). A chief cornerstone of the EU environmental plans in the field of air quality is the Air Quality Directive (2008). This directive sets a number of air quality standards not to be exceeded by a certain year. The communication on the ‘Clean Air Programme for Europe’ (2013) sets the short-term objective of achieving full compliance with existing legislation by 2020 at the latest, as well as the long-term objective of seeing no exceedances of the WHO guideline levels for human health.
An urban heat island is an urban area that is significantly warmer than its surrounding rural areas due to human activities. Urban heat islands are mainly due to substitution of forestry and agriculture with construction materials that absorb and reflect the incident solar energy. The increased temperature with respect to the countryside produces negative effects on animals and plants and impacts on the quality of rivers and underground water, as extra heat is harvested by rainwater through rain sewers and raisers.
Aside from the effect on temperature, heat islands can produce secondary effects on local meteorology, including the altering of local wind patterns and the rates of precipitation. The extra heat provided leads to greater upward motion, which can induce additional thunderstorm activity during summertime, responsible for local sudden flooding.
During summer heat waves, which intensity and duration increases over the years in southern countries, research has also shown how high temperatures are causes of heat strokes, heat exhaustions and of casualties in extreme cases.
As a consequence, heat islands are also indirectly responsible of unnecessary use of air-conditioners, therefore of unnecessary electricity consumption (U.S. Environmental Protection Agency. 2008. Reducing Urban Heat Islands: Compendium of Strategies).
This shows that the heating and cooling sector plays a key role in ensuring the success of the EU's transition towards an energy efficient and decarbonised economy, which in turn will allow mitigating the climate change, that energy sources are exploited, fostering resilient energy systems at European, national and mainly at local level, achieving long term energy security, accessibility and healthiness.
In this context, switching heating and cooling to renewable and other local sustainable resources (e.g. low temperature, residual sources of heat) is at the core of the European energy transition, which is underpinned by the Energy Union Communication COM(2015) 80 (A Framework Strategy for a Resilient Energy Union with a Forward-Looking Climate Change Policy) and by the Directives launched in November 2016 (under revisions now) in the package “Clean Energy for All Europeans”.
According to this documentation, it is important to develop tools that permit planning of heating and cooling to become a mainstream practice for public authorities and economic actors. Despite the existence of technically proven cost effective solutions, there is need to develop credible commercial models for energy delivery that would support wider market roll-out in the interest of the energy providers and of the final consumers (see focus in the Energy Efficiency Directive, draft 2016).
Life4HeatRecovery focuses on the recovery and re-use of waste heat from urban facilities, available at low temperature (lower than 40 °C) in DH networks.
The largest amount of waste heat available in the urban environment is rejected by air-conditioners, cooling systems in industrial processes and tertiary buildings (i.e. dry coolers and wet cooling tower), chillers of refrigeration systems and service facilities, e.g. sewer pipes. Data centers’ chillers and supermarkets’ refrigeration cabinets release a massive quantity of thermal energy: the refrigeration process in an average-size supermarket represents 50% of its energy uses, and can cover the heating needs of 200 apartments.
Recovering heat from dry coolers of industrial processes, i.e. at the very end of the cooling chain, does only require inexpensive piping works that do not interfere with the industrial production, facilitating the acceptance of the solution.
Clearly, recovering low temperature heat that cannot be used else how and re-using it to replace fossil fuels driven boilers installed at residential and tertiary buildings has a triple positive effect:
European Final Energy Consumption by technology used for production, 2014 data, Eurac Research from various sources, the legend refers to the outer ring.