HAP 1

[AbbyNormal]

I never use this program myself.

I am wondering if you can use it to check the loads over every month of the year.To look at Solar gain in cooling months otherwise not viewed as the time of peak cooling because of temperatures.

Southern glass is great for passive solar heating, but in a year round cooling scenario, some times it adds a lot more sensible load than was allowed for in the summer

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[DrRTU]

Under "Hourly Zone Loads" chose the time frame you need. The attached is from the HAP help screen.

 

[AbbyNormal]

thanks, looks like it does all 12 months

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[AbbyNormal]

Is the current version of HAP set up to run loads for UFAD?

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[cry22]

No UFAD in HAP 4.41
The new version of Trace 700 does.

 

[DrRTU]

Abby,
HAP does not model UFAD directly but with a few changes you can make it work. Review attached PDFs. I am doing UFAD with air columns (large fan powered boxes going in to the floor.

 

[AbbyNormal]

thanks Doc

I am reviewing a substantial job right now that was desigend with HAP.

I had seen in the ASHRAE guide how you divide up loads between the space and the plenum because of the stratification, get your CFM because of the room load, then use that CFM and the return load to come up with a return temperature.

I guess then the trick is to get the heat from the return plenum that goes into the floor slab above which reheats the supply air for the floor above.

What I have been noticing in my review though is an overly consrvative attempt to adapt HAP to UFAD in the project I am looking at. It seems to be double counting the plenum heat. It is carried as going right to the coil as return from one floor, then is carried again as heat transmitted through the slab to the zone above.

So I was a little excited to read the October 2007 Journal article on the UFAD calculations as it sounded like Berkely's CBE had a design tool available - basically a spread sheet that would convert the output of typical calc programs from say HAP, Elite etc, run for overhead systems into UFAD systems.

But, this design tool does not seem available yet.

No shortage of the ECM powerd fan floor boxes on this project.





Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[DrRTU]

Using a stratification layer concept, cooling loads in an UFAD model is complex. The trick in the model and real world is keeping the return plenum temperature high. Your floor slab temperature should be watched but I think it will not be a major load as compared to the plug load. A warm floor raises the floor supply temperate. I like using an overhead system to offset the skin loss. HAP will do the skin systems without any issues but sizing the interior air to the floor in a mixing application gets very tricky. 0.8 to 1 cfm/ft2 seams to pop up as a number - floor sat = 63 to 65.

The job I am working on now uses Four 12,000 CFM air columns per 28K floor plate and numerous ECM series boxes to offset skin losses. The series boxes have fan shifting to slow the fan down when setpoint is reached. Core areas are covered with conventional overhead VAV terminals.

 

[AbbyNormal]

plug load means equipment?

Computers and whatever is plugged in?

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[marcoh]

Thanks DrRTU! I am doing a large UFAD project at the moment and have tried to manipulate HAP in various ways to help with the the calculations. Will try this method and see how it compares to my other calcs.

 

[AbbyNormal]

give the man a star marco

Take the "V" out of HVAC and you are left with a HAC(k) job.