air conditioning EER, SEER and COP

need to talk about energy efficiency

we've been exposed to the co P for


what's ear energy efficiency ratio what

does it relate defined as the cooling

capacity that's Q dot removed from the

low temperature refrigeration divided by

the power input W dot in hey isn't this

Q dot low divided by w dot in yeah

they're the same definition they are

except this one

typically we put watts or watts and they

cancel it's the dimensionless this one

the ear they said we're interested in

cooling in beat to use per our

electricity and watts so they have these

funny units now they'll report it as a

number Oh my ear is ten with no units

but it's implied and you have to know

that it's ten BTU per hour per watt

alright so the ear has those units and

it's basically manufacturer reports it

for controlled environment thirty five

degrees C outdoor air and for the inside

air its twenty seven C and fifty percent

relative humidity so it has to work

while it's condensing some moisture

typical lean air conditioners have a ear

around ten nine nine and a half ten note

write this number down if you don't

already have it memorized one BTU per

hour is point two nine three watts if

you ever bought purchased appliances

maybe you've seen these tags

this is Energy Guide the US government

you know has a form for this tag and

encourages or requires manufacturers to

put it on their devices to help the

consumer make wise purchase decisions so

this is all about the manufacturer model

number rating over here oh it's for a

room conditioner with the reverse cycle

and with louvered sides here is a visual

of comparative comparative costs

estimated yearly operating cost if you

buy this unit Oh about $98

compared to if you bought a different

unit it could be down here so it looks

like it's a little bit on the high side

and they give you right here a 9.5 for

the ear now you can read these labels

with more confidence the air conditioner

has an ear of 9.5 just like we showed

what is the Co P is it 9.5 or is it a

different number

remember this conversion factor and go

for it so there's a lot of ways to

approach it but you just say that 9.5

BTUs per hour divided by watt that's

what was given that's our ears right EE

R is equal to that and if I multiply

this by hey over one BTU per hour is

equivalent to 0.29 three watts then I

just multiplied by a unit conversion

factor and BTUs per hour Watts watts or

or you can think of this is nine point

five two times point two nine three is

watts per watts which is COP right

so when we do that we find that it's

around two point eight makes sense once

you show it to me professor it makes

sense why don't you show me how to do

that before you ask me the question all

right now once you have ear down you

find out that ear is really used for

room air conditioners window units but

for the split system for your apartment

or house they use the seer seasonal

energy efficiency ratio all they do is

they have now on temperature conditions

for that low cannot location for United

States I think I don't think it's per

state where they bury it but it's for

seasonal temperature variations not for

a fixed condition now they're very close

a numeric value the ear and the seer but

they're slightly different in definition

because it's seasonal so again the room

air conditioner ears what's quoted split

system homes apartment Sears reported

typically the ear is here the seer is

much higher alrigh so the seer has units

of are those familiar they're the same

units they're the same exact units so

here is one showing a 13.3 seer now the

world continues to change back in oh six

there were some big changes where they

said if you're gonna sell anything in

the United States you must have at least

a 13 seer now I kind of remember when

that kicked in people in December of

five were selling Punch's units hey

cheaper prices going up we had to have a

higher efficiency I remember when my dad

bought a brand new unit for the house we

were living in when I was a kid and he

paid extra to get a 10 seer

high-efficiency unit really good today

you can't even get a 10 seer it's so

poor right it's so poor in efficiency

anyway over the years in 2015 they

bumped it up such that the southeastern

region the United States must sell only

14 seer or better and the world

continues to change

so what's southeastern region Alabama

Arkansas Delaware Florida Georgia Hawaii

hey let's show this graphically here 14

seer if you live in there they legally

cannot sell and install something less

than 14 seer now if you live up here

come on how much air condition do you

really need and went in this summer

you're nine months of winter all right

so you could still do 13 seer then

something about special over here so the

world changes and these requirements so

if the air conditioner has 14 seer what

is the coefficient of performance well

when you take the 14 x you've done this

before about 4.1 that's the Co P all


you should be able to do this I wish I

had more time but this is the type of

question you got somebody will say hey

you studied all this oh yeah see you're

oh yeah I learned all about Cyr I have a

13 seer system and some it needs to be

replaced somebody wants to sell me an 18

seer system if I go with the 18 seer

system the higher efficiency how much

money am I going to save on my electric

bill that's not a trivial question to

answer but you have all the tools and

should be able to answer it with the

number of assumptions a couple things is

and this is a friend of mine told me

this one he said well it's hard to

predict because look it when you get a

new car what do you like to do with your

new car you like to drive it you go on

road trips you show it off you don't

drive the same miles guess what your

fuel bill does for your new car it goes

up because you're driving it more you

get a new home air conditioning system

and you've kind of been laying in bed at

night sweating a little bit while you

try to go to sleep what do you do to the

thermostat of that new home air

conditioning system you drop that baby

down hey we're living in refrigerator

now and guess what you key now you can't

compare apples and apples oranges and

oranges you just started doing all kinds

of different things so what you have to

do is you have to assume that one summer

last summer is about the same as hot as

next summer I've ever seen a summer

where it really is kind of mild well

your electric bill is kind of mild to

that summer and then one summer it's

brutal and then as you're paying Whopper

bills the next thing is is you basically

had the same house in your same setting

on your temperature so that your your

cooling need for the house is about the

same as the cooling need for the house

you know it's related to the temperature

outside but it's also related to the

thermostat setting inside and maybe you

don't go on vacation for a month or

whatever so so here it is so if somebody

said this is how I calculate

cost to purchase electricity in one year

- cool only for the mountain electricity

not to do the laundry not to run the

pool pump not the electricity to run the

TV and different things it's just to

provide cooling air conditioning you

would say how much cooling do I need for

the whole year what is the rate of

electric consumption per cooling needed

and then what is my cost per the amount

of electricity that I need okay so

basically this is my one over the seer

that's what they're telling me here

right here the cooling / electric cost

okay that's ratio is this the here when

you invert this that's the seer okay or

just do the inverse of this year all

right now the second year the same thing

we want the same amount of cooling

that's going to be an assumption the

amount of electricity cost electricity

doesn't change all you're changing is

the efficiency of the system so what you

do is you say well the cost from the new

year the next year will be the cost from

the previous year $3,000 times a ratio

of the old cedar divided by the new seer

it should cost there there's an estimate

so what's my savings I'm gonna save what

eight hundred and thirty dollars it was

three thousand now it's eight hundred

thirty how much more did I pay you can

do a simple payback let's say you paid

twenty five hundred dollars extra to go

from the three C 13 seer to the 18 seer

how many years you know simple payback

you would take take that total amount

you save eight hundred and thirty

dollars per year one over a year and so

the time for payback would be whatever

that is what's that about for three what

is 25

the 8.30 three years three year payback

simple payback right so believe me this

is a type of calculation people want to

see and you're equipped to do it you're

equipped now to do it all right so we

covered a lot of material here hopefully

the ear and the sear you're now familiar

with let's continue on