Manual J Manual S Manual D Rescheck review FAQ

Written by Jobe Leonard of Rescheck.info. Jobe enjoys all things related to Rescheck reporting and the study of home energy audit softwares like Rescheck, Comcheck, and Manual J.

Jobe Leonard Rescheck.info

My comments on Manual J report attached.

1. General
2. Loads from windows appear to be high considering R-4 triple-glazed windows are specified.  Please check

Updated for R-4 

2. Infiltration heat losses seem high.  Please check assuming air tightness of 2.5 ACH

Updated for 2.5 ACH 

1. Continuous HRV with 80% SRE is specified for the house yet there are no loads due to ventilation indicated.

Updated Ventilation 

1. Latent cooling not calculated (or at least not shown).  Please comment

This shows up when you use the software option to look at all the reports together.  I attached a whole home Manual J so you will have this.

1. Internal loads not calculated (or at least not shown).  Please comment

A standard appliance package is added to your calculations.  

2. Main Floor
3. No heat loss shown for windows or walls, only infiltration.  Please comment

With the amount of insulation in your wall system and your climate zone the software zeroed out both of those calculations. The windows and walls were calculated, but the software was not provide a value.  I re entered the info and now it has calculations.

1. No heat loss through doors (2)

Doors are included. 

1. Can you provide a breakdown for the main floor 1) kitchen/living room and 2) bedroom?

Yes, I can. 

3. Basement
4. Heating and cooling load through basement windows exceeds main floor despite few window openings and no doors.

Updated.

1. 6074 BTUH for cooling seems excessive for a basement

Basements generally will be higher than main floor because they have the basement floor.  Since the main floor is capped by a heated area above and below then the floor and ceiling are not used in the calculations.

1. Latent cooling not indicated

This shows up when you use the software option to look at all the reports together.  I attached a whole home Manual J so you will have this.

1. Space consists of above grade and below grade walls yet report does not indicate loss through below-grade walls

The below grade wall option in the software does not offer the amount of insulation that is in your plans.  It caps at R-30.  The main floor has the option so the best solution was to get your correct R Value included and use other type of wall. 

1. Large heating load via infiltration.  Would we really expect this level of infiltration from a poured concrete basement with poly air barrier under slab?

Slab is insulated in calculation.  This is what the software suggests for an insulated basement floor of that size.

6 Attachments

Your previous whole house included Living Room and Kitchen reports.  Here is the correct whole house.

Let me know if anything else comes up.  I will be glad to help.

Attachments area

Your answer regarding basement cooling does not make sense (below).  It’s the cooling load I’m questioning.  Might be because you’ve assumed above ground walls?  If so, better to model as below grade walls, no?

1. 6074 BTUH for cooling seems excessive for a basement

Basements generally will be higher than main floor because they have the basement floor.  Since the main floor is capped by a heated area above and below then the floor and ceiling are not used in the calculations.

The basement floor is exposed to the exterior of the structure so it is included in calculations.

The main level’s floor is on top of a heated and cooled area so it is excluded calculations.Actually, I understand what you area saying.  Here is a new main floor and a new whole house that includes the new calculations for the main floor.Rob,

2 Attachments

A few comments/questions:

1. I am still struggling to understand what’s being predicted in the basement.

• For basement cooling, is 2400 BTUH internal cooling load due to HVAC equipment?
• For basement heating, there must be a way to run Manual J for insulated basements, no?  Using above grade walls appears to give incorrect results, as would be expected.  Can you re-run using below-grade walls where indicated on drawings, even if you have to use a lower insulation value to make it fit cool calc?

1. The new Main Floor calc does not match previous calculations for sum of kitchen/living rm and main floor bedroom.  Adding heat loads for kitchen/living rm and main floor bedroom totals 6652 BTUH, where as Main Floor result is 8,694 BTUH.  Which one is correct?
2. Heat load for Whole house does not match summed load for individual floors.   Whole house heating is calculated at 32,661 BTUH.  If I add individual floors I get 8093 (basement) + 8694 (main) + 9821 (2nd) = 26,608 BTUH.  Which one is correct?
3. Can you comment on what the AED graph tells us?

Thank you

Answers below in bold.

1. I am still struggling to understand what’s being predicted in the basement.

• For basement cooling, is 2400 BTUH internal cooling load due to HVAC equipment?

Yes, the software adds standard values for HVAC equipment.

• For basement heating, there must be a way to run Manual J for insulated basements, no?  Using above grade walls appears to give incorrect results, as would be expected.  Can you re-run using below-grade walls where indicated on drawings, even if you have to use a lower insulation value to make it fit cool calc?

Yes, new basement attached with below grade walls.

The new Main Floor calc does not match previous calculations for sum of kitchen/living rm and main floor bedroom.  Adding heat loads for kitchen/living roomm and main floor bedroom totals 6652 BTUH, where as Main Floor result is 8,694 BTUH.  Which one is correct?

The Kitchen Living and Bedroom are room specific.  The remaining BTU’s would be encompassed in the other areas of the main floor.  Ensuite, Booth, Study, Entry

1. Heat load for Whole house does not match summed load for individual floors.   Whole house heating is calculated at 32,661 BTUH.  If I add individual floors I get 8093 (basement) + 8694 (main) + 9821 (2nd) = 26,608 BTUH.  Which one is correct?

The Whole House.  It includes systems and latent loads that are shared by floors.

1. Can you comment on what the AED graph tells us?

This tells you the time of day that your structure will use the most the energy.  Based on your climate.

2 Attachments

Thanks response in red.  sorry for back & forth but I want/need to understand this if I’m going to size HVAC…

Answers below in red.

1. I am still struggling to understand what’s being predicted in the basement.

• For basement cooling, is 2400 BTUH internal cooling load due to HVAC equipment?

Yes, the software adds standard values for HVAC equipment.  Thanks

• For basement heating, there must be a way to run Manual J for insulated basements, no?  Using above grade walls appears to give incorrect results, as would be expected.  Can you re-run using below-grade walls where indicated on drawings, even if you have to use a lower insulation value to make it fit cool calc?

Yes, new basement attached with below grade walls.   –   basement heat load still seems high to me.  design temp at top of page is shown as -2F, which is air temp.   I hope the calculator is using earth temperature for below-grade heat loss calculation?

The new Main Floor calc does not match previous calculations for sum of kitchen/living rm and main floor bedroom.  Adding heat loads for kitchen/living rm and main floor bedroom totals 6652 BTUH, where as Main Floor result is 8,694 BTUH.  Which one is correct?

The Kitchen Living and Bedroom are room specific.  The remaining BTU’s would be encompassed in the other areas of the main floor.  Ensuite, Booth, Study, Entry   Understood thanks

1. Heat load for Whole house does not match summed load for individual floors.   Whole house heating is calculated at 32,661 BTUH.  If I add individual floors I get 8093 (basement) + 8694 (main) + 9821 (2nd) = 26,608 BTUH.  Which one is correct?

The Whole House.  It includes systems and latent loads that are shared by floors.  Understood thanks

1. Can you comment on what the AED graph tells us?

This tells you the time of day that your structure will use the most the energy.  Based on your climate.     

For whole house, AED shows 8-12 kBTUH.  actual peak load will be 32,661 BTUH.   what can I use AED for?   Is it relevant?

For the basement you can make personal adjustments lower as you see fit, but with the specs of your home and climate that is what the software provides for this project.  Subcontractors with local experience installing systems on similar houses can provide real life experiences of the best sized systems for your square footage and insulation levels.

AED is your glazing load.  So how much your glazing areas will add to your load per hour.  So in the afternoon the south/west sun will peak your load.  After sunset (19 hour) the load drops to zero.