Rating System

LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.2

Inquiry

This credit interpretation request is in reference to the modeled baseline HVAC system. The project is a 142,000 sqft health care facility to be built in Northern Italy. Two questions arise due to the location and use of the building. 1) The pressurization and air change requirements of a health care facility meet exception (c) of G3.1.1 which indicates System 3 - PSZ-AC is to be used as the baseline system. A single zone constant volume system is unable to adequately meet the temperature and humidity control requirements without reheat and would not be used in this type of facility. Omitting the reheat capabilities of the baseline system puts the design model at an extreme disadvantage when comparing energy use and does not seem to meet the intent of the standard. It is proposed that for this project reheat also be included in the baseline model to account for the temperature and humidity control requirements of a health care facility. 2) Italian health care facilities require substantial fan energy due to high air change rates, AHU components and duct accessories compared to other facilities such as office buildings. The intent of this section 3.1.2.9 was to enable credit for and encourage more efficient fan systems. The only pressure credit given is for systems requiring filtering systems in excess of 1 in. w.c. static pressure. Air pressure drops associated with cooling coils, preheat coils, multiple filter stages, air blenders, extensive sound attenuation required by Italian law, humidifiers, exhaust bio-safety cabinets, and excessive number of fire and smoke dampers due to Italian law all contribute to the excessive fan energy required. It is proposed this calculation not be used to penalize the design model for meeting Italian health care facility requirements and to determine the baseline system fan power on the same static pressure as the proposed design. Great effort was put forth to provide an energy efficient HVAC design while meeting or exceeding the design requirements. Both of the issues stated penalize this effort and therefore would not be the intent of the standard.