What is the proper way to represent a door which happens to have glass? According to 90.1, doors that are more than one-half glass are considered fenestration. So in a program like HAP, should all of the doors with more than 50% glass area be entered as windows or do you still enter them as doors with a U-value for the opaque portion, plus a separate U-value and shading coefficient for the glazed portion?
If the glass area is less than 50% of the door area, is the glazing U-value and shading coefficient governed by different minimum requirements than if the glass area was more than 50% of the door area?
Let's say you have a 21 sqft metal frame entrance door with a small 1.3 sqft sight glass in it. Would the glass portion requirements be dictated by "Metal framing (entrance doors)" under Fenestration in Tables 5 of 90.1? Would the rest of the door be dictated by Opaque Doors "Swinging" then? What if the glass area in that example was more like 18 sqft of the door? Would it be treated any differently?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
November 1, 2013 - 11:54 am
Doors are modeled as doors and windows as windows. Doors with glass in them would be modeled with the glass in the door and either an overall assembly U-value or modeled separately as glazing and framing.
Matt Scott
EngineerN.E. Fisher & Associates, Inc.
18 thumbs up
November 1, 2013 - 12:01 pm
So what is the significance of 90.1 considering a door with more than 50% glass to be fenestration? Regardless of the amount of glass content, all doors are modeled as doors?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
November 1, 2013 - 12:06 pm
The impact would be related you your previous question on vertical glazing area and the 40% maximum. They define fenestration as not being opaque. So the glass in the doors counts as glazing area but a door is still a door.
Matt Scott
EngineerN.E. Fisher & Associates, Inc.
18 thumbs up
November 1, 2013 - 1:04 pm
Ok, thanks!
Fatou Jabbie, | Technology | Design and Engineering Plan Reviews | Energy Code Compliance | Sustainability | LEED AP BD+C
Founder and PrincipalUSL Technology Inc.
3 thumbs up
September 30, 2019 - 6:11 pm
Hi Marcus,
I am going to piggyback on the above question for additional clarification on modeling HM doors on the perimeter of the building. The opaque doors are not labelled and therefore considering to use the following U-factor value from A7.1: "Insulated metal swinging doors, including fire-rated doors, insulated access hatches, and insulated smoke vents: 0.50"
1) Installer provided a certificate stating that with 1.75 inch thickness for the unlabelled HM doors with R-26 Rockwool insulation inserted under the hats and between the ribs of internal steel stiffeners, it's U-0.13. Is there any additional information should be asking them to support this claim, so I don't have to default to using the 0.50 U-factor per Appendix A7.1?
2) There is a variety of HM door types from Corridors leading to MECH rooms and bathroom, that I intend to model. These HM doors have features such as "kick plates with louvers". Is it necessary to model these interior doors considering temperature differential in these spaces?
Thank you in advance.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
October 1, 2019 - 4:54 pm
U0.13 sounds like a point calcualtion. U0.5 sounds much more reasonable and realistic for an overall value.
You don't need to model the interior doors, especially if the spaces are adiabatic and air just flows through them.