Hi,
We are working on a Fuel-Station divided into two buildings joined by a canopy area that covers de pumping islands. The North building (4383 ft2) includes the minimarket, fastfood, restrooms and kitchen. The South building (2570 ft2) includes 5 offices, 2 employee resting areas, restrooms, and changing rooms. The air conditioning design is also divided in two different systems.
The North building has 3 rooftops, one for each area, while the South building has one split per conditioned space (7 for offices and resting areas plus 1 for the data center). The air conditioned system was designed this way for two reasons: 1- The North building is designed for 24h use and is the most crowded area (238 persons estimated simultaneously at peak hour); 2- The South building offices and employee resting areas will be sporadically used, for a few hours and probably not simultaneously (at the most 6 persons in the offices areas, three of which are employees that work in boxes and use the office just for payments; plus 1 or 2 in the employee resting area). The design team defined that using splits (with occupancy sensors) instead of a central system, would be more efficient according to our working schedule.
Questions:
Does ASHRAE 90.1-2007 allow an installation of these characteristics for our type of building, and combining Rooftops and Splits?
In case it does, the selected rooftops will comply with Table 6.8.1b of ASHRAE 90.1-2007. The problem is that the Splits equipment available in our country seem not to comply with the standard. When we asked the HVAC consultant he told us that a new government restriction prohibits importing foreign equipment. Is there any chance USGBC could take this into account?
Thanks
David Hubka
Director of OperationsTranswestern Sustainability Services
527 thumbs up
May 5, 2011 - 7:43 am
ASHRAE 90.1-2007 allows the installation of rooftops and Split Systems.
LEED requires project teams to demonstrate, at a minimum, a 10% improvement when compared to baseline building as modeled in accordance with ASHRAE 90.1-2007, Appendix G. However, every single building item (envelope, HVAC, lighting, etc...) by themself, is not required to meet the efficiency requirements - per LEED. You only need to prove that the building / Energy systems as a whole, when operating in full expected occupancy, exceed the standard. I've run models where parts of the envelope did not meet the standard however the proposed building exceeded ASHRAE 90.1 by the required minimum.
Your splits should not exclude you from the prereq.
Guillermo T. Adamo
ArchitectSursolar
55 thumbs up
May 6, 2011 - 7:20 am
Thank you David,
I understand your comment, but LEED asks the compliance with ASHRAE 90.1-2007 SECTIONS 5.4, 6.4, 7.4, 7.4, 8.4, 9.4 and 10.4. Section 6.4 also requires compiance with tables 6.8.1. So, isn´t this necessary for split systems?
Thanks
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
May 6, 2011 - 9:24 am
There was a discussion related to this issue here:
http://www.leeduser.com/credit/CS-2009/EAp2
See EA P2- ASHRAE 90.1 Compliance discussion.
Guillermo T. Adamo
ArchitectSursolar
55 thumbs up
May 10, 2011 - 7:49 pm
Dear Marcus,
I read the discussion forum that you recommended, and still dont quite understand. The product we are using figures in the link below:
http://www.tempstar.com/products/dfac.html
We assume that the equipment belongs to table 6.8.1B. of ASHRAE 90.1-2007 Is this right? All the splits in the building are below 19kw Size category, and should perform (according to the same table) at a minimun efficiency of 3.81 SCOP (cooling mode) and 2.25 SCOP for heating mode (size under 40KW category).
The efficiencies shown in the technical sheet we recieved from the manufacturer, are below the SCOP reference for cooling mode, and above the reference value for heating mode.
Can we still achive EAP1 using this HVAC systems?
Thanks a lot,
Willy
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
May 11, 2011 - 9:20 am
OK regarding your first question - 90.1-2007 has no problem with you installing a combination of roof top units and splits. Equipment efficiency is a mandatory provision. You must meet the mandatory provisions and show the 10% savings. If your splits do not meet the efficiency requirements then technically you do not comply with a mandatory provision and cannot earn the prerequisite.
Based on your earlier posts I was not sure if the issue was related to equipment that was tested according to the ARI Standards that 90.1 requires. If it is then yes it must meet the minimum efficiencies in Table 6.8.1A. I can't tell from what you provided for sure but Table 6.8.1B covers heat pumps not standard split systems.
Julia Weatherby
PresidentWeatherby Design & Co. Engineers
94 thumbs up
May 11, 2011 - 9:31 am
It does appear to me that even if you model the building and use the Section 11 compliance path of ASHRAE 90.1-2007, the equipment efficiency tables still apply because they are referenced in Section 6.4, Mandatory Provisions.
In your position, I would fill out the credit template saying I was proposing an alternate method for meeting the requirement. Point out that split system equipment meeting the efficiency tables is not available in your country and that importation of such equipment is forbidden. You would add strength to your argument by explaining why split equipment is better suited to those sections of the building than other types of equipment available to you that do meet the efficiency tables. If you can still show the LEED-required level of energy savings in your building as a whole compared to the modeled base building that does meet the equipment efficiency requirements, it seems reasonable that LEED would accept your alternative method in this special case. There are no guarantees, but I would be optimistic.
You might want to submit for design certification review well in advance before installation of the split systems, so there might be time to substitute a different type of equipment if feasible in case LEED were to turn down your proposed approach.
Guillermo T. Adamo
ArchitectSursolar
55 thumbs up
May 17, 2011 - 7:07 pm
Marcus, Julia:
Thanks for the reply. It's been very useful for us.
I have another question that involves our previous discussion. The North building (fed by the 3 rooftops) has a window to wall ratio of 78%. The South building (fed by the splits systems) has a ratio of 26%. If i take into account all fenestration and above-grade walls in both buildings, the ratio becomes 56%.
My question is:
1- Considering that the two separate buildings are indeed only one fuel-station, when determining the total fenestration gross area of the building, should i make an average of the two sectors?
2- If the average is the correct path, should i reduce the fenestration surface only in the North building till i get to the 40% window/wall ratio considering both buildings?
2b- Or should i reduce the fenestration area in the North building till i get to the 40% ratio in it? Regardless of the South Building? I get confused here because each building works with totally independent HVAC systems, and where the envelope is less efficient is just were most people will be (238 peak compared to 8 of the south building)
Thanks a lot
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
May 17, 2011 - 7:25 pm
If they are two separate buildings then you will need to show compliance for both individually. Assuming this is the case - the north building would be 78% in the proposed model and 40% in the baseline. The south would be 26% in both.
If they are one building then determine the overall window to wall ratio. If the overall building design is over 40%, model the design as designed and then reduce the baseline model to 40%.
Guillermo T. Adamo
ArchitectSursolar
55 thumbs up
May 18, 2011 - 9:18 am
Thank you Marcus,
I still doubt about considering it as a single building since we have 2 bodies joined by a canopy where the pumping islands are set. They have different uses, on one hand the market and on the other the offices.
How do you think I should consider it?
Thank you,
Willy
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
May 18, 2011 - 9:38 am
Based on the little I know it sounds like separate buildings and each must show compliance independently.
Jean Marais
b.i.g. Bechtold DesignBuilder Expert832 thumbs up
May 29, 2012 - 10:42 am
"The south would be 26% in both." ...so if I plan a building with <40% glazing, I won't be rewarded here...interesting.
CT G
23 thumbs up
May 5, 2015 - 1:35 pm
Isn't there an error in table 6.8.1B - SI Edition?
Where it says "Air cooled (heating mode) <40 kW (cooling capacity)" shouldn't say "<19 kW (cooling capacity)"?
The reason I ask this is because in the same table it says "Air cooled (heating mode) >=19 kW and <40 kW (cooling capacity)" and in the IP Edition, for the same size category (described in SI Edition as "Air cooled (heating mode) <40 kW (cooling capacity)") it says "Air cooled (heating mode) <65.000 BTU/h(cooling capacity)" which is equivalent to 19 kW.