The project is a speculative office highrise building, where the Owner will rent floors, or portion of floors, to multiple tenants. The owner will supply Core & Shell HVAC equipment including a central boiler plant, floor-by-floor water-cooled DX equipment, and cooling towers that serve the owner-provided DX units and any supplemental tenant-installed DX units for data rooms, etc. The owner also provides lighting for the Core and Shell spaces (public lobbies, elevators, bathrooms, garage). The tenants provide all partitions, HVAC distribution, appliances, equipment and lighting in their areas, and any supplementary DX equipment mentioned above. We want to clarify whether the calculations for percentage of energy cost savings under LEED-CS EAc1 should be performed using the total energy cost of the building, or only the energy cost for the Core & Shell. PROPOSAL: We propose to calculate the percentage savings as follows: 1. Model the energy consumption for the entire building > For the Design Model, model the building envelope, the Core & Shell areas, lighting, elevators, plug loads and any other equipment controlled by the Owner according to the design. For the Baseline Model, create a model that complies with the requirements of ASHRAE/IESNA Standard 90.1-2004 Appendix G. > Since tenants are unknown, assume that the lighting in tenant spaces of the Design Model is in accordance to the requirements of the ASHRAE/IESNA Standard 90.1-2004 -- the same as in the Baseline Model. > Assume that the plug loads in the tenant spaces of the Design Model is the same as in the Baseline Model. The plug loads will be no less than 25% of the electricity use of the Design Model. 2. Calculate the energy cost for the entire building - both Design and Baseline models 3. Calculate the energy cost paid for by the tenant, i.e., for uses over which the tenants have control. This energy use is identical for both the Design Model and the Baseline Model: > Lighting in tenant spaces > Plug loads in tenant spaces > Any DX equipment installed by tenants in their spaces 4. Subtract the cost of tenant-controlled energy use from the total cost: (2) - (3). This yields the energy cost for the Core and Shell for both Design and Baseline Models 5. Calculate the percentage savings per LEED-NC and LEED-CS method, using the energy costs for the Core & Shell, as noted in (4) above. We request USGBC\'s ruling on whether this method of calculating percentage energy savings for Core & Shell projects is acceptable. JUSTIFICATION: We believe that this method meets LEED requirements based on the following reasoning: 1. Consistency with other LEED CS credits: The above methodology is consistent with other LEED-CS credits. LEED-CS is intended for the portion of the building that is controlled by the Core & Shell project team, as opposed to the portion of the building that is controlled by the tenant design team. For example, Material Resource credit calculations are based on the cost for the Core & Shell portion only. No cost is assumed for the tenant fitout areas. 2. Correlation between LEED-NC 2.2 and LEED-CS 2.0: The same percentage savings is required to obtain energy points under both LEED-NC 2.2 and LEED-CS 2.0, yet buildings under LEED-CS 2.0 have less opportunity to reduce the energy cost, since Core & Shell developers do not control tenant fitout. If the percentage savings are calculated using the total energy cost (not just the Core and Shell energy cost), the Core and Shell of a LEED-CS building would have to perform much better than the Core & Shell of a LEED-NC building, to make up for the lack of available energy cost reductions in tenant areas. Examples of energy savings that can be achieved within tenant spaces, and that are not available to the Core & Shell Developer, include but are not limited to the following: 1. Lighting load reduction > Reduce lighting density below that of ASHRAE/IESNA Standard 90.1-2004 (the Standard) > Motion detector sensors in areas where they are not already required by the Standard > Perimeter daylight dimming > Lumen maintenance depreciation system for core spaces > Addressable lighting 2. HVAC controlled by tenants > If the HVAC system is configured for fan-powered VAV boxes, or if the HVAC system employs fan-coils, use electronically-commutated motors > Water-cooled DX equipment more efficient than required by the Standard > DDC controls of terminal units 3. Plug load reductions > EnergyStar computers and appliances > Power management software > Motion detection sensors for computer monitors While in very rare circumstances the Developer may mandate certain (but not all) energy cost features to the tenants, including such requirements in the lease is unfeasible for the great majority of Core & Shell developments. In summary, it is our understanding that LEED CS and LEED CI were created to acknowledge the limits of control over design and construction in these project types when compared to owner-occupied buildings (the typical LEED NC project). Our proposed approach to credit EAc1, we believe, is in keeping with this intent.
The applicant is requesting acceptance of proposed modifications in the calculation methodology used for this credit. The proposed methodology is not, however, acceptable as it significantly modified the approved calculation methodology. The applicant should note that the methodology published in the LEED-CS v2.0 Reference Guide was balloted and approved by the USGBC members and cannot be modified via a CIR. The applicant should also note that for Core and Shell, credit can be taken for any energy efficiency measure required by the owner and enforced through the leasing requirements. Examples of these may include limiting installed lighting power or the type and efficiency of HVAC equipment.