above
city
conducting
construction
district
energy
engineering
equipment
fuel
gas
ground
heat
hot
housing
hydropower
industrial
industry
infrastructure
insulation
iron
line
main
metal
old
pipe
pipeline
piping
plant
power
serve
service
sky
snow
steam
steel
stream
structure
supply
support
system
technology
thermal
transfer
transit
transmission
transportation
tube
tubing
urban
water