Dryer energy usage comparison

	A	B	C	E	F	G	I	J	K	L
1	By Joe Rice
2	Inputs are in yellow.
3	Source for some of these numbers:	michaelbluejay.com/electricity/laundry-sources.html
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5	General Inputs
6	Cost of electricity	$0.15	per kWh
7	Cost of gas	$1.40	per therm
8	COP of central heating system (mini-split)	3.0
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10	Energy loss to venting			Traditional electric (vented)			Heat-pump dryer
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12	Inputs						Inputs
13	dryer exhaust rate (cfm)	150	cfm	energy required to dry a load	3.30	kWh	Energy usage relative to traditional electric	50%
14	indoor temp (C)	20	°C	energy required to heat makeup air	0.43	kWh	energy required to dry a load	1.65	kWh
15	outdoor temp (C)	0	°C	% energy that stays inside house	5%		% energy that stays inside house	100%
16	time required to dry a load (hr)	0.75	hr	energy that stays inside house	0.165	kWh	energy that stays inside house	1.65	kWh
17				energy saved/used by mini-split	0.055	kWh	energy saved/used by mini-split	0.55	kWh
18	Constants			total cost per load	$0.55		total cost per load	$0.17
19	specific heat of air	1005	J/kg°C
20	density of air	1.205	(kg/m³)
21	ft³ per m³	35.31		Traditional gas (vented)
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23	Convert exhaust rate from cfm to kg/hr
24	dryer exhaust rate	4.25	m³/min	gas energy required to dry a load	0.22	therms
25	dryer exhaust rate	255	m³/hr	elec. energy required to dry a load	0.21	kWh
26	dryer exhaust rate	307	kg/hr	energy required to heat makeup air	0.43	kWh
27				% energy that stays inside house	5%
28	mass of air exhausted per load	230	kg	energy that stays inside house	0.32	kWh
29	mass of makeup air per load	230	kg	energy saved/used by mini-split	0.11	kWh
30	energy that must be added to makeup air to bring it to indoor temp	1.29	kWh	total cost per load	$0.39
31	energy required by mini-split to heat makeup air	0.43	kWh
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46										http://michaelbluejay.com/electricity/laundry-sources.html
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