welcome back to the honeybee for
grasshopper tutorials and we've been
through envelope geometry and materials
program internal mass control loads and
schedules we're going to finish up now
with natural ventilation and HVAC
systems for the natural ventilation of
the object that you should place onto
the canvas is here at sorry honeybee set
EP air flow there and this gives us a
few different options for how we want to
deal with air flow in the zone the first
thing I should point out is that energy
Plus as a simulation engine is a it
makes a very important assumption that
all of the air in the zone is fully
mixed that is it doesn't stratify it
doesn't um have differential thermal
properties based on solar radiation or
adjacency to walls or anything like that
it is one zone it's a sort of watertight
zone or air tight zone and there's one
temperature of air inside that zone it's
a relatively simple kind of model to do
more complex modeling it requires
entirely different type of program
structure a lot more complex a lot
longer runtime and the accuracy of it is
questionable so the so this is actually
a very good simulation modeling type but
it does have this limitation or
assumption and that limitation is
something you need to keep in mind as
you are modeling the thing that that
energy plus knows is what the air coming
air temperature coming in as well as the
speed and and level elevation and it
knows the air speed and temperature
going out
and and it's sort of a closed system it
doesn't know or doesn't take into
account the presence of exterior
obstacles so like this building that I
have next door it's not going to know
that this window here is probably
obstructed from a lot of air flow or
that this tree might be blocking air
flow into this window so these are
things that that you need to take into
account in understanding how you're
modeling the airflow because Energy Plus
does not that being said it is possible
to model a variety of different types of
air flow including fans or windows or
even stack ventilation and this
component here gives you sort of the
window into that Interzone airflow is
for multi zone models and I'm not
covering all the zone models in this
this set of tutorials so I'm going to
skip that the next one is natural that
elation type and you can see that
there's four basic options no natural
ventilation window natural ventilation
custom stack and wind ventilation and
then fan driven ventilation so the so
there's a few different options and
depending on which one you select these
inputs are populated differently so
actually I'm going to pull the slider so
you can see this if we connect 0 was was
no natural ventilation these all go away
so there's nothing going on there
just Zone in zone now we're done can
actually attach a panel here and it
doesn't give us any information but it
will so now if we go to number one with
window natural ventilation you'll see
that this populates and this is kind of
cool it automatically reads the area of
the windows that we have expand this
even more here their zone one is a
circus with glaze the area five point
seven square meters has an operable
area of 2.9 square meters and effective
area the operable portion is 2.9 square
meters and in a whole bunch of other
things that relate to buoyancy in the
zone and these you can set right here
you can set when the window is going to
open and close so a minimum indoor
temperature and a maximum indoor
temperature and you probably want to
align those with the thermostat set
points for your heating and cooling
systems the minimum outdoor temperature
for natural ventilation so that it's not
too cold you're not getting cold air in
and the maximum outdoor temperature so
that you're not bringing in really hot
air into the to the zone and so why
don't we go ahead and set those maybe
for 21 degrees Celsius for my minimum
and since I think my cooling setpoint is
probably going to be around 26 degrees
I'm going to put my maximum natural
ventilation of 25 degrees and that way I
won't have windows open when I've got
the air conditioning on for the minimum
outdoor temperature I'm going to say
that say 15 degrees so I'll see them
maybe 18 degrees Celsius is it's about
right and then the maximum outdoor we
can put it say 30 degrees Celsius and so
anytime the outdoor temperature is less
than 30 degrees or between 18 and 30 and
the indoor temperature is between 21 and
25 we'll get natural ventilation then
you can set a schedule that can be 8760
hours of when that open or closed say
you have some times when it can't be
open then you can use this I'm going to
skip it for now and just assume it's
always open when it can be and then a
fraction of glazed area that's operable
so it automatically read how much area
was on that but if I want to say that
there's only 50%
the window is operable then this will it
should change it the effective operable
area is 2.9 20 years I think that we
have a 4 was the oh right so it's off by
default it is assumed that 0.5 is the
default so we can change this if we want
the whole thing saves a casement window
we have the whole window of be operable
at a hundred percent there then you can
see this changes to a hundred percent
being operable and similarly you can set
the love the glazing height this is the
glazing area the glazing height the
fraction that is operable you can also
change these discharge coefficients
either wind or stack which would prevent
stack ventilation from coming in or from
or wind coming in so you can read more
about that if you hover over it
explains it really well so that's
natural ventilation and going to group
these guys all together keep this nice
and organized and move on to HVAC
systems so as I mentioned for the
National ventilation the zone is one
airtight zone with sort of a closed
volume of air contained in it and
EnergyPlus natively has a lot of ways of
modeling different types of HVAC systems
for this tutorial and probably just to
get you started the there's something
called an ideal air loads system that is
the sort of beginner system the easiest
one to set up and use and you can find
that here at honeybee set ideal air
loads parameters there and so like
everything else take your HB zones and
swing it through here and then
hook up your data so now we've got the
HVAC and there's just a few simple sets
of things to input here one is whether
you have outdoor air for how it it sets
outdoor air and this actually relates
directly to setup inputs we had before
for internal loads and back here at
ventilation for area and ventilation for
person we said how much air flow is
moving through the zone this is
basically air for breathing and here we
can set whether the or how the HVAC
system delivers that air it can be
delivered as you can say none you don't
want it to deliver any of that air so in
which case you'll see that there's as
much less airflow there's no airflow
through the zone or you can see it do it
as a maximum of ventilation or some of
ventilation actually 62 which is what
most jurisdictions are using their
standard for fresh air requires the sum
of those so and this is by default set
as the sum I think well if it's not
maybe we should make sure that it is by
putting in number two there and then
looking at the readme which says zone
one has this outdoor air requirements
set to some so that's right you can also
set the cool supply air in love the
heating supply air temperatures I like
to leave these default I think if by
default it it's a 50 degrees Celsius and
15 degrees Celsius
there's no hover over instructions here
but I'm just going to leave those and
then the max cooling and heating
capacity if you wanted to set that the
danger of setting that is that you could
have times when the system requires more
heating or cooling than
able to provide and so it would skew
your energy results so that's it for
HVAC systems the only other thing that
you need to know about this is again
this is an ideal load system so it is
supplying just as much heating or
cooling as it's needed to satisfy the
thermostat set points those thermostat
set points were set back here under
schedules at heating setpoint schedule
including SEP 1 schedule we can see that
heating cooling setpoint schedule pretty
quickly by looking at visualizing the
set points using this these components
and here we can see that looks like the
heating setpoint is between 20 to 21
degrees during most of the day and then
16 degrees during the night with a more
set back in the summer and so 16 to 21
degrees and then the cooling is between
24 is it's 24 during the day and 27
night time set back so that gives you an
idea of what the what the HVAC system is
is set to and actually that makes me
think that this I did not set my natural
ventilation correctly should be about a
23 probably in order to not overlap with
the cooling
so let's run this and and see where we
are in terms of our energy use with this
system that we set up and the while it's
running the ideal load system provides
just as much energy as you need to heat
or cool to that setpoint and it is not
taken to account the coefficient of
performance COP of the actual systems
the cooling or heating systems and so
you really need to post process that
part of it on to the results so let's
see if we have any errors zero errors
there's a whole bunch of warnings and it
looks like these are standard warnings
so here I've hooked up electrical
equipments lights heating and cooling
and so you see there's 7500 kilowatt
hours of cooling 1276 of heating but in
order to tell how much actual heating
and cooling energy you would use you
need to multiply it by the coefficient
of performance and so for instance a
standard heat pump for cooling would
probably have a co P of about 4 or 5 so
you'd actually divide by say 4 so 7 5 0
8 divided by 4 would give us the actual
energy use for that system standard
boiler might be around Co P of about 0.8
so you would divide 12 76 divided by
pointing to get the actual heating
numbers so I hope that helps explain the
HVAC systems and ventilation systems and
provides a quick overview of all these
with a vetted assumptions and data in
the HP zone component there's a lot here
a lot more to play with and to
to look at but I think this should get
you started and get rolling the last
thing I wanted to mention was that it's
as you get deeper into energy modeling
get more comfortable with it it's always
good to go to the source itself and one
of the really great things about
honeybee is it makes it pretty
transparent so if you go to the folder
where your work is being saved here you
can see this IDF file which is what is
being what is what is running the
simulation and if you double click on
that IDF file that will open this EP
launch browser window and from here
there's all kinds of ways to access the
native data the sort of most useful is
probably this IDF editor where you can
open it and see press control L and
you'll just see the the classes that
have been populated and you can see all
the different things that we just set so
for instance the ideal load system you
can see it has the maximum heating
supplier air about 50 degrees in the
next minimum cooling 13 and it's using
the outdoor ventilation rates that we
set as a sum etc etc and so each one of
these different objects has all that
smarts embedded in it and it's all
should be quite transparent out of the
inputs from honey-b into here the IDF
and ultimately it's the IDF that's being
run by Energy Plus by the same token if
you want to know more about Energy Plus
or you're having questions or problems
this help menu is a fantastic place to
start the energy plus input-output
reference is a highly detailed
compendium you can see it's 2200 pages
of all of the different inputs and
outputs that Energy Plus can give you
and this is not what I would call
pleasure reading but it's a good way of
if you have any questions to search
through this and try to find the right
answers so I think that's a good place
to leave you a good luck in your energy
modeling have fun enjoy and until next
time I'll sign off