a	ambient
b	booster
c	consumer; cold reservoir
dst	destruction
el	electric
elb	electric-boiler booster
ex	exergy
gas	gas
gbb	gas-boiler booster
gen	generated
h	hot reservoir
hpb	heat-pump booster
hx	heat exchanger
i	input
loss	losses
m	constant, mean
n	constant
pump	pumping
r	return
s	supply
scw	sanitary cold-water
shw	sanitary hot-water
tot	total
w	water