[Bldg-sim] ventilation only & LEED

[christian stalberg]

The warehouse section of our facility in El Salvador is to be ventilated only.  The textile section of the same building will be cooled and humidity will be controlled. Other areas such as offices and cafeteria will be cooled. There is no heating load in El Salvador. I reviewed inquiry 5088 (copy below) which would suggest the warehouse should be modeled with air conditioning in both the base case and the proposed case even though no cooling will be provided.  Our building is a little different than the building in inquiry 5088 in that it has no heating load.  Therefore by the 90.1 standard, the standard does not apply (section 2.2) and it is an unconditioned space.  We feel the ventilated section of our building should be rated based on energy savings of standard ventilation equipment versus the proposed high efficiency fans and louvers that we are providing for ventilation.  We would like to proceed with the ventilated enclosures being included in the model without heating or cooling.  Please advise.

 

 

      Inquiry Number: 
     5088 
     
      MPR/Prerequisite/Credit: 
     EAc1: Optimize Energy Performance 
     
      Posting date: 
     11/27/2007 
     

 

   

It is not acceptable to allow spaces to exceed the unmet load hour requirements of the ASHRAE 90.1-2004 Appendix G methodology. This is a similar situation to naturally ventilated spaces, which are required to include cooling systems to meet space loads in the proposed case even if the actual building will contain no cooling. Building owners may always choose to turn off HVAC systems, or not have them installed at all to conserve energy, but the ASHRAE modeling protocol assumes that cooling systems will be installed and run with sufficient capacity to meet space loads. The applicant may use a set-point of 80 degrees Fahrenheit for the maintenance bays, but cooling system capacity must be increased until the requirements of ASHRAE 90.1-2004 section G3.1.2.2 are met. The project may still receive credit for using an efficient cooling system as compared to the ASHRAE baseline cooling system.

 

    Inquiry [] 

       
     Our project is located in Las Vegas and consists of a combination of office spaces and maintenance bays for earth-moving equipment. The owner is a large agency that sells, rents and repairs such equipment; these repairs are done both inside and outside the building envelope. The maintenance bays are occupied by mechanics and will be conditioned with evaporative coolers and gas furnace heat, the system supplies 100% outside air. This cooling system provides conditioning of the spaces but is not able to meet all peak loads for a climate such as Las Vegas even when these spaces are modeled with higher setpoint at 80 degrees. In reality, if the maintenance bays go above the temperature setpoints, the mechanics will continue work in the warmer conditions or take a break. This is not difficult for maintenance bays, where some of the work will also done outdoors with no conditioning at all. The owner does not want to fully condition the maintenance bays with the intention of achieving high levels of energy efficiency. We propose the following modeling approach for EA Credit 1. -Baseline model will have a mechanical system based on Table G3.1.1A of Appendix G with 80 degree temperature setpoint for the maintenance bays. -Proposed Design model will have the system as designed in the building that provides partial conditioning with the same 80 degree temperature setpoint. We will not model additional compressor cooling for hours where the system is not able to meet loads. This approach will result in exceeding the difference in the unmet load hours beyond 50 as required by Appendix G. However, this is a conscious decision by the owner who wants to maximize energy efficiency by providing limited conditioning through evaporative cooling for the maintenance bays, and allow the temperatures to float higher during peak conditions. We feel that this approach appropriately captures the intent of the design, and gives credit to the energy efficiency measures being taken. It also provides a way for demonstrating the value of an energy efficient approach to the community in Las Vegas where compressor cooling is increasingly used, often indiscriminately; this is a desert climate and a different approach to comfort and conditioning is possible. Is this approach acceptable? If not, can you advise us on an alternative approach that addresses the desire of the owner to demonstrate high levels of energy efficiency for using such a system?
     

 
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