I am in need of help with EAp2 Section 1.4 tables.xls. This project is for new construction.
1. What means “Semi-conditioned”? The storage space has only heating and ventilation, is this means “semi”?
2. “Unconditioned Total Fan Power”, is it fan for parking garage? According to ASHARE 90.1-2007 parking garages with natural or mechanical ventilation are not considered enclosed spaces. Therefore it is not “unconditioned space”.
3. The baseline case is with system 8 and the cooling load is lower than 300 tons. I choose the COP for chiller from table 6.8.1.C. Is it wrong? According to “EAp2 Section 1.4 tables.xls“ Efficiency should be from tables 6.8.1A, 6.8.1B, or 6.8.1D. The baseline heating Type is electric resistance, which table (tables 6.8.1B, 6.8.1D, or 6.8.1E) should I use?
Thanks!
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5912 thumbs up
May 23, 2011 - 9:35 am
Semi-conditioned is defined in the beginning of the Standard under "space".
Again refer to the defintion of space - an enclosed space can also be unconditioned.
That is the correct Table (6.8.1C) for a screw chiller in the baseline. Enter the efficiency values in Table 1.4.3 HVAC Water Side. I think it is an omission in the form to not include Table 6.8.1C. There is no table for electric resistance heating. Its efficiency is always 100%.
Yu Wang
Mechanical EngineerSCHOLZE Consulting GmbH
13 thumbs up
May 25, 2011 - 9:48 am
Thanks Marcus. But I did not quite understand. Is “Semi-conditioned” the same as “semiheated space” in ASHARE?
And I have another question for “G3.1.3.12 Supply Air Temperature Reset” How to calculate the supply air temperature resetting, if the max room temperature is 26.5 °C? What means “the minimum cooling load conditions”?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5912 thumbs up
May 25, 2011 - 4:30 pm
Sorry for the confusion. I am using semi-conditioned and semi-heated as the same term.
This section refers to the supply air discharge temperature, not the room temperature setting. The supply air temperature is reset up to 5 degrees F above design temperature if the cooling load can be met with the warmer air. This serves the purpose of reducing the reheat requirements in other spaces served by that system.
Yu Wang
Mechanical EngineerSCHOLZE Consulting GmbH
13 thumbs up
May 26, 2011 - 5:32 am
Thank you for the reply again. Bellow I have described how I caculate my Baseline Case, please would you correct this.
There are 5 AHU systems in proposed case for Office, Restaurant, Lobby and Storage. The proposed systems have no return air, and supply airflow rate is the minimum outdoor air. Therefore in baseline case I calculate the fan power and the design airflow rate for each system.
1. Minimum outdoor airflow rates are identical with the proposed case (G3.1.2.5). The min OA for office is 91,200 m³/h.
2. For Office the space heating load is 192 kW and cooling load is 313 kW. The baseline airflow was calculated base on 313 kW and a delta T 20 °F (SA to RA). The result is 84,510 m³/h and smaller than min OA (91,200 m³/h). According to G3.1.2.8 the required ventilation air is larger, therefore the design airflow rate is identical with min OA.
3. The min RA is 20 °C and the max RA is 26.5 °C (79.7 °F).The SAT was calculated as follows:
Tzone – Tdesign = 20 °F
79.7°F – 59.7 °F = 20 °F
Treset = Tdesign + 5 °F =59.7 °F +5 °F = 64.7 °F
The air temperature for cooling will be reset to 64.7 °F
Thanks a lot!
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5912 thumbs up
May 31, 2011 - 12:56 pm
1. yes OA must be identical
2. It is OK that the baseline would come out less than the proposed
3. The 20F delta T should be based on the cooling room temperature setting. If that is 26.5C then you are correct.