Central Park East (CPE) is a 26 story office building with retail on the first level, 9 floors of parking above the retail, and approximately 490,000 sf of office above the parking area. This development is a very unique development, particularly in downtown Phoenix, which has not seen any major new office buildings in nearly fifteen years. Our project is building on an existing surface parking lot in downtown Phoenix, is adjacent to the Arizona State University downtown campus and is directly across the street from the Valley Metro Rail and Regional Public Transportation Authorities downtown bus hub. We began the design of the CPE project in its current state in early spring of 2006 and are going to break ground in early October of this year. The overall building design and in particular the MEP and building enclosure systems, were designed to meet specific requirements of the LEED-CS program as it stood in early 2006 with the full intent to pursue certification. The issue that we are now facing with regard to CPE is that we did not register the CPE project prior to the June 26, 2007 rating system change which now requires the (2) Optimize Energy Performance credits. Unfortunately for our project, we are now up against a wall. Based on our timing for groundbreaking, a number of the scopes have already been bought and released. The primary challenge we are facing is that a redesign and scope modification to meet the new requirements would be extremely costly and would impact our schedule substantially. As designed, we currently exceed the performance requirements of ASHRAE 90.1-2004 Chapter 11 for the Energy and Atmosphere Prerequisites; the building exceeds energy requirements by 4% and costs by 10%. Since we are not able to meet the specific requirements of the now required (2) Optimize Energy Performance credits, we would like to propose an alternate plan to achieve the 14% cost savings for the building. Based on the whole building energy simulation under appendix \'G\' , we are operating at 97% of ASHRAE 90.1-2004, leaving us with a deficit of 17%. We propose to close this 17% gap with the following methods: -Require tenants through the lease(s) to design to no greater then 0.9 Watts/SF for their lighting build out. This will result in a minimum increase in energy performance of 2.6%. -Switch "high efficiency" motors to "premium efficiency" motors. This will result in a minimum increase in energy performance of 1.0%. -The balance of the energy optimization, 13.4%, to get to the +14%, will be handled through the purchase of energy from a renewable source(s) as defined by the Center for Resource Solutions (CRS) Green-e product certification requirements for the life expectancy of the building (50 years). We did also review the use of the higher efficient coolant (R-22) in the water cooled Dx system designed for this project. This would have increased the energy efficiency of the building by approximately 4.7%, however, there are considerable environmental and longevity concerns with using the R-22 coolant. Therefore, this option was not pursued beyond the initial study. In addition, we also studied the installation of a 50kw -150kw photo voltaic array on the roof of the building. Due to limitations of available roof area, high perimeter parapets and shading through the winter and partial spring and fall by a taller building to our south, we were not able to effectively design a viable PV array on the roof of this building. Building a sustainable building and obtaining LEED-CS certification for our CPE project is very important to our team , future tenants and public at large; we really want to make this happen. Although the above proposal does not necessarily meet the exact intent of the recent LEED - CS 2.0 requirement of two Energy Performance credits, we feel that based on the timing of our design, trade buyout, and groundbreaking for the project, that the same end goal will be achieved.