# Bathroom fan



## ELLEN09US (Dec 9, 2020)

Hello,
If the bathroom has a window, do I still need a fan? 
Thanks!


----------



## fatboy (Dec 9, 2020)

Operable window = fan not required.


----------



## mark handler (Dec 9, 2020)

*Yes, in CA it is required to have a FAN
California Residential Code 2019*
R303.3.1 Bathroom Exhaust Fans
Each bathroom containing a bathtub, shower or tub/shower combination shall be mechanically ventilated for purposes of humidity control in accordance with the California Mechanical Code, Chapter 4; and the California Green Building Standards Code, Chapter 4, Division 4.5.
*Note: Window operation is not a permissible method of providing bathroom exhaust for humidity control.

California Green Building Code 2019*
4.506.1 Bathroom Exhaust Fans
Each bathroom shall be mechanically ventilated and shall comply with the following:
Fans shall be ENERGY STAR compliant and be ducted to terminate outside the building.
Unless functioning as a component of a whole house ventilation system, fans must be controlled by a humidity control.
Humidity controls shall be capable of adjustment between a relative humidity range of ≤ 50 percent to a maximum of 80 percent. A humidity control may utilize manual or automatic means of adjustment.
A humidity control may be a separate component to the exhaust fan and is not required to be integral (i.e., built-in).
Notes:
For the purposes of this section, a bathroom is a room which contains a bathtub, shower, or tub/ shower combination.
Lighting integral to bathroom exhaust fans shall comply with the California Energy Code.


----------



## JCraver (Dec 9, 2020)

How does that make any sense, especially for a "green" code?  To require a device that uses electricity, while disallowing opening a window?  The bathroom fan manufacturers lobby must be tougher than I thought...


----------



## mark handler (Dec 9, 2020)

JCraver said:


> How does that make any sense, especially for a "green" code?  To require a device that uses electricity, while disallowing opening a window?  The bathroom fan manufacturers lobby must be tougher than I thought...


Solar power
Fans reduce mold and mildew, increasing the indoor air quality.
It does *not*  disallow a window opening.
Based on human nature, not many will open the window if they have to step into the tub/shower to do it.
How many will open a window with 100+ degree, outside air temperature?
How many will open a window with -32 degree, outside air temperature?


----------



## JCraver (Dec 9, 2020)

Ok.  But opening a window reduces mold and mildew as well.  Especially in most of California, where there is no outside humidity to start with - you open the window, and all that humidity rushes out to fill the void.

I just have a hard time with a code that purports its purpose as saving energy then requiring devices that use energy, when a passive system serves the same purpose.  It's some shady science that would assert an energy-saving finding by requiring an electric fan when an openable window is present.


----------



## Pcinspector1 (Dec 9, 2020)

JCraver said:


> I just have a hard time with a code that purports its purpose as saving energy then requiring devices that use energy, when a passive system serves the same purpose. It's some shady science that would assert an energy-saving finding by requiring an electric fan when an openable window is present.


Goof point JC.

My Las Vegas bathroom at EDUcode had a small crank-out window, seem to do just fine. There was no need for a bath fan.


----------



## classicT (Dec 9, 2020)

Washington State also requires a fan. No exception for a window.


----------



## fatboy (Dec 9, 2020)

Didn't say I agreed with it, that it is in the unamended published code.


----------



## ADAguy (Dec 9, 2020)

mark handler said:


> Solar power
> Fans reduce mold and mildew, increasing the indoor air quality.
> It does *not*  disallow a window opening.
> Based on human nature, not many will open the window if they have to step into the tub/shower to do it.
> ...


maybe it depends on who pays for utilities, tenant vs landlord as to whether to use the fan/or not?


----------



## Pcinspector1 (Dec 9, 2020)

Forgot to mention the additional wall or roof penetration's that are required with the fan exhaust....they make a charcoal type bath fan, looks like that would be banned too!


----------



## mtlogcabin (Dec 9, 2020)

Depends on the climate zone you are in and the infiltration rate

2018 IRC

R303.4 Mechanical ventilation.
Where the air infiltration rate of a dwelling unit is 5 air changes per hour or less where tested with a blower door at a pressure of 0.2 inch w.c (50 Pa) in accordance with Section N1102.4.1.2, *the dwelling unit shall be provided with whole-house mechanical ventilation in accordance with Section M1505.4.*
M1505.4.4 Local exhaust rates.
Local exhaust systems shall be designed to have the capacity to exhaust the minimum airflow rate determined in accordance with Table M1505.4.4.


TABLE M1505.4.4
MINIMUM REQUIRED LOCAL EXHAUST RATES FOR
ONE- AND TWO-FAMILY DWELLINGS


AREA TO BE
EXHAUSTED    EXHAUST RATES    
Kitchens    100 cfm intermittent or 25 cfm continuous   
*Bathrooms-Toilet Rooms    Mechanical exhaust capacity of 50 cfm intermittent or 20 cfm continuous    *


----------



## ELLEN09US (Dec 9, 2020)

Thanks all!


----------



## mark handler (Dec 9, 2020)

JCraver said:


> Ok.  But opening a window reduces mold and mildew as well.  Especially in most of California, where there is no outside humidity to start with - you open the window, and all that humidity rushes out to fill the void.
> 
> I just have a hard time with a code that purports its purpose as saving energy then requiring devices that use energy, when a passive system serves the same purpose.  It's some shady science that would assert an energy-saving finding by requiring an electric fan when an openable window is present.


NO longer an option.


----------



## mark handler (Dec 9, 2020)

ADAguy said:


> maybe it depends on who pays for utilities, tenant vs landlord as to whether to use the fan/or not?


NO longer an option.


----------



## JCraver (Dec 9, 2020)

mark handler said:


> NO longer an option.



I get that it's not allowed.  I just don't agree with it, because it's stupid.


----------



## rogerpa (Dec 9, 2020)

mtlogcabin said:


> Depends on the climate zone you are in and the infiltration rate


2015 IRC
*R303.4 Mechanical ventilation.
Where the air infiltration rate of a dwelling unit is 5 air changes per hour or less *where tested with a blower door at a
pressure of 0.2 inch w.c (50 Pa) in accordance with Section N1102.4.1.2, the dwelling unit shall be provided with
whole-house mechanical ventilation in accordance with Section M1507.3.

*N1102.4.1.2 (R402.4.1.2) Testing.*
The building or dwelling unit shall be tested and verified as having an air leakage rate of *not exceeding five air
changes per hour in Climate Zones 1 and 2, and three air changes per hour in Climate Zones 3 through 8. *Testing shall
be conducted in accordance with ASTM E 779 or ASTM E 1827 and reported at a pressure of 0.2 inches w.g. (50
Pascals).

Ergo, every dwelling requires whole-house ventilation.


----------



## ICE (Dec 9, 2020)

rogerpa said:


> Ergo, every dwelling requires whole-house ventilation.


and the fan operates 24/7


----------



## Robert (Dec 9, 2020)

I was recently in some apartments that did permitted interior renovations. All had 24/7 whole house ventilation added. The fans were located in the bathroom ceilings, and the apartment was always cold...the fan was sucking cold air in from the exterior through the wall mounted AC units and any other crack and crevice it could find! Their electric bill went through the roof...could not keep the place warm. Did the installer get something wrong? I thought those units would warm the incoming fresh air through a heat exchanger. The Panasonic units have 2 pipes both mounted on an exterior wall...one intake, one exhaust.


----------



## mark handler (Dec 10, 2020)

Robert said:


> I was recently in some apartments that did permitted interior renovations. All had 24/7 whole house ventilation added. The fans were located in the bathroom ceilings, and the apartment was always cold...the fan was sucking cold air in from the exterior through the wall mounted AC units and any other crack and crevice it could find! Their electric bill went through the roof...could not keep the place warm. Did the installer get something wrong? I thought those units would warm the incoming fresh air through a heat exchanger. The Panasonic units have 2 pipes both mounted on an exterior wall...one intake, one exhaust.


Talk to the Mechanical Engineer, Fan May have Been too Powerful or maybe it should be on a timer or Humidistat


----------



## Rick18071 (Dec 10, 2020)

Robert said:


> I was recently in some apartments that did permitted interior renovations. All had 24/7 whole house ventilation added. The fans were located in the bathroom ceilings, and the apartment was always cold...the fan was sucking cold air in from the exterior through the wall mounted AC units and any other crack and crevice it could find! Their electric bill went through the roof...could not keep the place warm. Did the installer get something wrong? I thought those units would warm the incoming fresh air through a heat exchanger. The Panasonic units have 2 pipes both mounted on an exterior wall...one intake, one exhaust.



If the apartments are that leaky they don't need and shouldn't have the fan.


----------



## tmurray (Dec 10, 2020)

The issue with opening windows and any device that requires occupant interaction, is that most people don't know how to use them properly. There is an ASHRAE joke about the best way to make buildings more comfortable to occupants is to not give them access to control it.


----------



## JCraver (Dec 10, 2020)

rogerpa said:


> 2015 IRC
> *R303.4 Mechanical ventilation.
> Where the air infiltration rate of a dwelling unit is 5 air changes per hour or less *where tested with a blower door at a
> pressure of 0.2 inch w.c (50 Pa) in accordance with Section N1102.4.1.2, the dwelling unit shall be provided with
> ...





ICE said:


> and the fan operates 24/7



Not if the homeowner has any brains at all.  

Every new furnace and A/C system we put in around here has an outside air intake plumbed into the air handler from the factory, and everyone is installing programmable t-stats nowadays.  That's all the IRC, IECC, and IL Energy codes require.  Make sure the t-stat has a selectable position that just says "fan" and you've met every requirement for the whole-house ventilation in the code.  Nowhere in the code does it say the homeowner has to flip that switch (or push the button) to turn the fan on so it runs all the time.


----------



## JCraver (Dec 10, 2020)

tmurray said:


> The issue with opening windows and any device that requires occupant interaction, is that most people don't know how to use them properly. There is an ASHRAE joke about the best way to make buildings more comfortable to occupants is to not give them access to control it.



Right, I agree.  But code shouldn't try to regulate dumb@$$ disease.  There's not enough trees for the pages that would take.


----------



## tmurray (Dec 10, 2020)

JCraver said:


> Right, I agree.  But code shouldn't try to regulate dumb@$$ disease.  There's not enough trees for the pages that would take.


I agree to a certain extent. Some of us are seeing people who are creating some very serious issues by not knowing how their mechanical systems function. I've seen indoor air quality issues and even structural degradation. Educated builders are well aware of this. Bathroom exhaust fans get tied into lighting so that someone HAS to turn it on when the room is in use. They go to great lengths to educate home owners on how to use the mechanical ventilation of their home. But, I still see most of these units turned off because "they waste energy". 

The question is always to what level does the state protect the individual from themselves. I think if you asked 50 different people, you'd get 50 different answers and not a single one would be wrong. Seat belts are perhaps the best example of this. You don't buckle up, you are the one who suffers the consequences. There are rarely better direct cause and effects like this. But, in many places, it is still required by law for everyone to fasten their seat belts. 

We're getting dangerously close to political here, but I think we can all respect one another's views on what should and should not be regulated. Ultimately, we vote our conscience and the majority rule.


----------



## rogerpa (Dec 10, 2020)

ICE said:


> and the fan operates 24/7


Not necessarily.
*M1507.3.2 System controls.*
The whole-house mechanical ventilation system shall be provided with *controls that enable manual override.*

IOW the occupant can shut it off.

M1507.3.3 Mechanical ventilation rate.
*Exception:* The whole-house mechanical ventilation system is permitted to operate intermittently where the system has controls that enable operation for not less than 25-percent of each 4-hour segment and the ventilation rate prescribed in Table M1507.3.3(1) is multiplied by the factor determined in accordance with Table M1507.3.3(2).

I agree that this is "nannyism" at its highest level. A majority of governmental (Code) employees put this in the code.


----------



## mark handler (Dec 11, 2020)

JCraver said:


> Not if the homeowner has any brains at all.


Sometimes the contractor  does not follow wiring directions and bypasses the  intermittent operation.
I have seen where they bypass the built-in humidistat, as well.


----------



## Paul Sweet (Dec 11, 2020)

The object of the energy code is to save energy, not the house or its occupants.


----------



## mark handler (Dec 12, 2020)

Paul Sweet said:


> The object of the energy code is to save energy, not the house or its occupants.


But the Green and Mechanical Codes, which is where the requirement is, try's to create a healthy interior environment. 
The ultimate goal, in CA, is to have it run on solar, saving energy purchases from commercial sources.


----------



## Mac Moonfire (Dec 19, 2020)

"we the North" are required to have a bathroom fan unless the room is tied to a HRV that runs continuously. 9.32.3.6.(1)(b)

Also, we have a "passive ventilation" option for dwellings less than 1800ft², on a single level, and in a coastal climate. A 2 speed fan is installed in the main bathroom and will exhaust 19CFM 24/7 and a minimum of 49CFM when the occupant flips the fan switch. Minimum 4in² (ø2¼") passive air vents are required in every bedroom and one in the common living space for makeup air. 9.32.3.4.(6)
It's a cheap way to install a code conforming ventilation system but an expensive solution for the occupants who pay the energy bill. This option won't be available to us in 2023.


----------



## AdCornish65 (Feb 7, 2021)

I think there should be a fan in every bathroom to provide humidity control even though you have a window there. Moreover, I've heard that there is a law that the house owner must install such a fan, and if one of the services detects its lack, you will face a large fine. Actually, I have a question about the solar roof exhaust fan, that's why I found this thread. Please tell me if someone installed such a fan and if you are satisfied with its work. I want to know if it's worth buying. Well, I have a stuff in my attic that's dear to me as a memory and recently I found mold on its ceiling and an unpleasant smell there, I think that the problem is in the ventilation and I want to solve it. Any thoughts?


----------



## Mac Moonfire (Feb 7, 2021)

AdCornish65 said:


> I think there should be a fan in every bathroom to provide humidity control even though you have a window there. Moreover, I've heard that there is a law that the house owner must install such a fan, and if one of the services detects its lack, you will face a large fine. Actually, I have a question about the solar roof exhaust fan, that's why I found this thread. Please tell me if someone installed such a fan and if you are satisfied with its work. I want to know if it's worth buying. Well, I have a stuff in my attic that's dear to me as a memory and recently I found mold on its ceiling and an unpleasant smell there, I think that the problem is in the ventilation and I want to solve it. Any thoughts?


Any bathroom or kitchen fan venting in the attic? either directly or by leaks?
How is the ventilation of your roof? Do you have good cross ventilation? from soffit to ridge/gable/roof vents?


----------

