The applicant appears to be requesting clarification for the following questions: [1] can a national database be used to determine the energy consumption of residential spaces, [2] can alternative operative temperature ranges be specified for the mechanically conditioned model when comparing to the naturally conditioned model, and [3] how is the energy savings from natural ventilation calculated. The responses to each of the questions are as follows: [1] Yes, a national database can be used to determine the receptacle and process loads for residential spaces, which are discussed in ASHRAE Appendix G Table G3.1 Number 12. The national database must be a well established, reputable source. When preparing for submission, please be sure to include the name and a brief description of the national database used to determine the residential loads. Please note that the baseline and design case receptacle and process loads must be equal. The baseline case residential space lighting power, however, must be determined according to ASHRAE Appendix G Table G3.1 Number 6. Additionally, the thermal loads for the residential spaces must be determined by conducting an energy model that satisfies the requirements of EAc1 in the LEED-CS v2.0 Reference Guide. [2] While ASHRAE 55-2004 specifies different operative temperature set points for establishing thermal comfort in mechanically and naturally ventilated spaces, this approach is not acceptable for EAc1 modeling. ASHRAE 90.1-2004 Appendix G Table G3.1 Number 1 (b) states that temperature and humidity control set points must be the same for the proposed and baseline case. [3] The proposed building must be modeled such that when natural ventilation can not provide the necessary cooling, cooling from a mechanical system is provided. The energy savings associated with the natural ventilation system are equal to the difference between the baseline system cooling load and fan energy and the cooling load and fan energy of the proposed system (i.e., natural ventilation with "backup" mechanical cooling). See related CIR ruling dated 3/22/07. Please note that additional documentation is required to verify that natural ventilation is an appropriate design strategy to satisfy the criteria of EAp2 and EAc1 and should be submitted with the credit applications for review. Specifically, the project team must address the project\'s local climate and the applicability of the climatological conditions with regard to natural ventilation system design. The project must provide design documentation to verify that the natural ventilation system\'s design is comprehensive and the energy savings and thermal comfort provided by the proposed system are quantifiable. The system design must also either provide an automated control system to control all or part of the building openings or provide a compelling narrative that indicates the system will be operated to maintain thermal comfort conditions with a high level of confidence.