This paper presents a review of the environmental impacts of most heating systems drawing together published literature on the subject, not previously available. Here, a comparison between the different systems such as coal, wood, oil, natural gas, heat pump, geothermal and solar energy is provided in terms of their environmental impact. The most important parameters considered are the emission rate and toxicity. This places the coal-fired system as the worst among all heating systems regarding the impacts on the environment. On the other hand, renewable energy sources are the most preferred sources decreasing total emissions and air pollution. In order to make a comparison between the different systems, the emissions that must be taken into consideration are CO, CO2, NOx, SO2, PMs, N2O, CH4, volatile organic compounds, polycyclic aromatic hydrocarbons and aldehydes.
NomenclatureASHP air source heat pump ATES aquifer thermal energy storage BTES borehole thermal energy storage CCHP combined cooling, heating and power CHP combined heat and power DH district heating DHC district heating and cooling DS district system EF emission factor GE geothermal energy GHG greenhouse gas GSHP ground source heat pump HEPA high efficiency particulate air HP heat pump IWH industrial waste heat LPG liquefied petroleum gas NG natural gas PAH polycyclic aromatic hydrocarbons PM particulate matter SNG synthetic natural gas SPF seasonal performance factor VOC volatile organic compounds WHR waste heat recovery Subscripts 2.5 particles with diameter less than 2.5 micrometres 10 particles with diameter less than 10 micrometres