# Library with operable windows in lieu of mech ventilation?



## BayPointArchitect (Sep 2, 2015)

Applicable code:

2009 IMC

3,000 S.F. library

calculated ventilation required: 510 CFM

Question:

Given that this building will have a split mini system, can operable windows be provided in lieu of an ERV or some other type of system?

Thank you!


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## fatboy (Sep 2, 2015)

Section 402;

*SECTION 402 NATURAL VENTILATION*

*402.1 Natural ventilation.* _Natural ventilation_ of an occupied space shall be through windows, doors, louvers or other openings to the outdoors. The operating mechanism for such openings shall be provided with ready access so that the openings are readily controllable by the building occupants.  

*402.2 Ventilation area required.** The minimum openable area to the outdoors shall be 4 percent of the floor area being ventilated. * 

*402.3 Adjoining spaces.** Where rooms and spaces without openings to the outdoors are ventilated through an adjoining room, the opening to the adjoining rooms shall be unobstructed and shall have an area not less than 8 percent of the floor area of the interior room or space, but not less than 25 square feet (2.3 m**2**). The minimum openable area to the outdoors shall be based on the total floor area being ventilated. * 

*Exception:** Exterior openings required for ventilation shall be permitted to open into a thermally isolated sunroom addition or patio cover, provided that the openable area between the sunroom addition or patio cover and the interior room has an area of not less than 8 percent of the floor area of the interior room or space, but not less than 20 square feet (1.86 m**2**). The minimum openable area to the outdoors shall be based on the total floor area being ventilated. *

*402.4 Openings below grade.** Where openings below grade provide required **natural ventilation**, the outside horizontal clear space measured perpendicular to the opening shall be one and one-half times the depth of the opening. The depth of the opening shall be measured from the average adjoining ground level to the bottom of the opening. *


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## steveray (Sep 2, 2015)

503.2.6 Energy recovery ventilation systems. Individual fan systems that have both a design supply air capacity of 5,000 cfm (2.36 m3/s) or greater and a minimum outside air supply of 70 percent or greater of the design supply air quantity shall have an energy recovery system that provides a change in the enthalpy of the outdoor air supply of 50 percent or more of the difference between the outdoor air and return air at design conditions. Provision shall be made to bypass or control the energy recovery system to permit cooling with outdoor air where cooling with outdoor air is required.

Exception: An energy recovery ventilation system shall not be required in any of the following conditions:1. Where energy recovery systems are prohibited by the International Mechanical Code.2. Laboratory fume hood systems that include at least one of the following features:2.1. Variable-air-volume hood exhaust and room supply systems capable of reducing exhaust and makeup air volume to 50 percent or less of design values.2.2. Direct makeup (auxiliary) air supply equal to at least 75 percent of the exhaust rate, heated no warmer than 2°F (1.1°C) below room setpoint, cooled to no cooler than 3°F (1.7°C) above room setpoint, no humidification added, and no simultaneous heating and cooling used for dehumidification control.3. Systems serving spaces that are not cooled and are heated to less than 60°F (15.5°C).4. Where more than 60 percent of the outdoor heating energy is provided from site-recovered or site solar energy.5. Heating systems in climates with less than 3,600 HDD.6. Cooling systems in climates with a 1-percent cooling design wet-bulb temperature less than 64°F (18°C).7. Systems requiring dehumidification that employ series-style energy recovery coils wrapped around the cooling coil.


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## skipharper (Sep 3, 2015)

What about the energy code and air changes per hour?


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## conarb (Sep 3, 2015)

skipharper said:
			
		

> What about the energy code and air changes per hour?


How are you going to deal with that with open windows?  Too many people getting sick in sealed up buildings, everybody is going back to opening windows, a few years ago a Handlery Hotel in San Francisco was remodeled and was running radio ads saying something like: "Come back to Handlery, we now have real opening windows."


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## mtlogcabin (Sep 3, 2015)

2009 503.2.6 is C403.26 in the 2012 and has changed a little.

I don't believe a "mini split" system will fall within the code requirements of the above sections


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## steveray (Sep 3, 2015)

mtlogcabin said:
			
		

> 2009 503.2.6 is C403.26 in the 2012 and has changed a little.I don't believe a "mini split" system will fall within the code requirements of the above sections


Probably not, but wouldn't want it to be overlooked...


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## BayPointArchitect (Sep 4, 2015)

Thanks everyone.


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