ND-v2009 GIBp2: Minimum building energy efficiency Required

The project consists of a consumer products manufacturing facility.The energy intensive manufacturing process exceeds an estimated 90% of the facility\'s total energy load. The Project Client has developed a new manufacturing process which consumes approximately 15% less energy per produced than the previous generation process.The new proprietary process has recently been installed at a similar facility and energy reduction has been demonstrated. Since industrial energy for manufacturing is not covered by ASHRAE 90.1-2007 and the building cannot be accurately modeled using the Appendix G method, project team is seeking to establish and obtain approval of an alternative compliance path.Following the Appendix G procedure would be very challenging because there are so many interacting process and non-process systems. Artificially segregating the systems in the model would not reflect energy consumption patterns accurately. Focusing on non-process components that represent less than 10% of the total energy consumption would not demonstrate the majority of the facility\'s energy savings. Manufacturing process improvements targeted at the other 90% of energy usage have a much greater impact on the entire facility\'s energy consumption. Instead of creating an energy model, baseline and proposed energy consumption will be compared by utilizing an Energy Consumption Index (ECI), which is recognized by the Association of Energy Engineers as an accepted methodology for calculating energy consumption in a manufacturing facility. The Project Client has tabulated historical overall site energy data and production at an existing facility which uses only the previous generation manufacturing platform and is also tabulating data from a site with new generation equipment. The energy data from both of these plants is not sub-metered between process and building loads because there is little economic benefit to meter the small building-only loads. An alternative compliance path will be established using the overall site ECI. Please verify that the following method may be used for determining the entire facility\'s energy cost savings.PROPOSED COMPLIANCE PATH:1. Baseline Building:The existing baseline site

This LEED Interpretation pertains to the requirement to limit voltage drop for Energy & Atmosphere Prerequisite 2 for Minimum Energy Performance. The current limit is posing a significant hardship to tall buildings relative to satisfying the mandatory requirements of ASHRAE Standard 90.1-2007 (also applicable in 90.1-2010), referenced in the prerequisite.
Specifically, the requirement in Standard 90.1 to limit voltage drop to not greater that 2% for electrical feeders and 3% for branch circuits (section 8.4.1) has proven to be problematic for large projects which often contain feeders of extended length. By comparison, the National Electric Code does not explicitly regulate voltage drop, but suggests model Code language that limits either electrical feeder or branch circuit voltage drop to 3%, with the combined voltage drop of both feeders and branch circuits when added together not to exceed 5%.
This may appear to be a minor difference, However, when applied to long copper electrical feeders which are present in tall buildings, this absolute constraint from Standard 90.1 on the feeder voltage drop (of 2%) results in a significant increase in the required quantity of copper conductors and associated conduit.
As an example of a higher density regions attempting to resolve this issue, the New York City Electrical Code has adopted the National Electric Code model language as mandatory for all buildings and also included an exception for residential occupancies within buildings to limit electrical feeder voltage drop to 4%, and the combined voltage drop of both feeders and branch circuits to not more than 5%.
This change is in recognition of the inherently short branch circuit lengths in typical NYC apartments, and is based on measured testing results which indicate that voltage drop is often negligible due to the conservative feeder and circuit sizing requirements mandated by other aspects of the Code. Thus, for residential buildings the allowable voltage drop of 4% is twice the allowable voltage drop of 2% as required in 90.1. Depending upon the length and capacity of a particular feeder, this difference can equate to a 3X variance in the required quantity of copper conductors and conduit, with a significant associated cost premium.
The magnitude of the cost premium to satisfy the 90.1 criteria in tall buildings, as compared with New York City Code requirements, can be equal to the total of all of the other cost premiums (hard and soft) associated with achieving LEED certification (at the Silver or Gold level) for a medium to large project in New York City.
In order to resolve this issue, we are proposing an alternate compliance path that we believe would meet the intent of the prerequisite, while at the same time preventing cost prohibitive use of significant amounts of additional copper.
Voltage drop is literally the loss of electrical energy (converted to heat) within a building, therefore regulating voltage drop is no different than regulating the energy efficiency of any electricity consuming device in a building (such as light fixtures or HVAC motors).
Several approaches could be implemented within the LEED rating system to address this disproportionate prescriptive requirement of Standard 90.1. A simple and straight forward approach would be to allow buildings utilizing Appendix G energy modeling as the LEED energy compliance path to include voltage drop as a regulated parameter within both the Energy Cost Budget and Design Energy Cost models. Under this approach, the 90.1 criteria (2% for feeders and 3% for branch circuits) would included in the Energy Cost Budget model, but the Design Energy Cost model would be allowed to include the actual voltage drop that will be implemented in the project design.
This approach would achieve the direct intent of the voltage drop requirement of Standard 90.1 in regulating the energy efficiency of power distribution systems, but through the inherent trade-off methodology of Appendix G would allow projects the flexibility to eliminate a disproportionate cost premium that is otherwise incurred by a prescriptive requirement.

We request a ruling regarding building ventilation and its impact on EAp2/EAc1. The question is two-fold: (1) Will USGBC/GBCI allow credit for a design that increases ventilation effectiveness other than Displacement Ventilation (a noted exception for PDV now exists in ASHRAE 62.1-2010), and, (2) will USGBC/GBCI allow credit for reduced ventilation by decoupling the outdoor air from the multi-zone VAV system, which requires increased ventilation rates to ensure the appropriate airflow is reaching all of the zones? Project Design Information:The project is a multi-story office space undergoing a major renovation. In accordance with ASHRAE Standard 90.1-2007 Appendix G, the baseline system is System 8. Ventilation is handled by VAV air handling units, thus requiring multi-zone calculations. Due to elevated terminal heating temperature, zone air distribution effectiveness (Ez) is 0.8.Similarly, the proposed system will employ a VAV system, but with decoupled constant-volume ventilation, thus foregoing multi-zone calculations and reducing outdoor air. Ventilation is room neutral resulting in an Ez of 1.0.Referenced Standards/Guidelines/Research:Ez factors and ventilation rates are determined from ASHRAE Standard 62.1-2007 Tables 6-2 and 6-1, respectively.ASHRAE Standard 90.1-2007 Appendix G Section G.3.1.2.8 Design Airflow Rates states:(D)esign supply airflow rates for the baseline building design shall be based on supply-air-to-room-air temperature difference of 20°F
This exceeds the 15°F limit from Table 6-2. ASHRAE 62.1-2007 User’s Manual (page 6-27) instructs to use the worst case factor, which is the heating Ez of 0.8.
ASHRAE Standard 90.1-2007 Appendix G Section G.3.1.2.5 Ventilation states:
(V)ventilation rates shall be the same for the proposed and baseline building designs.
Reviewing the User’s Manual for this section adds:
(V)ventilation can be a major contributor to building energy consumption, but it is not considered an opportunity for energy savings... (V)ventilation is energy neutral as far as tradeoffs are concerned.
Spare a recent exemption for using PDV to reduce outdoor air rates via an allowable manipulation of Ez, no other exemptions exist. Yet, ASHRAE research recognizes the advantages of decoupling ventilation in its ability to reduce ventilation volume and therefore energy costs. From Jeong, J.W., et. al, ASHRAE Transactions 2003, Volume 109, Part 2:
“All-air [VAV] systems are widely used in many types of buildings, [even though] these common systems have several significant deficiencies. …(T)he multiple spaces method must be used to increase the [OA fraction... This increase… may add significantly to energy consumption and operating cost…
“The challenge of conforming to [ASHRAE Standard 62] in an energy efficient manner can be met with a dedicated outdoor air system (DOAS)… The DOAS provides 100% of the required ventilation air at constant volume”
In addition, EPA’s Technical Report PNNL-18774 (Strategies for 50% Energy Savings in Medium Office Buildings) recognized DOAS as a primary energy savings strategy using the previous research by ASHRAE noted above as support and justification.
Conclusions:
It is clear that, as written, the ventilation volumes should be the same in both models. But we respectfully ask the LEED® Reviewer to provide us feedback on whether this makes sense for the current LEED® Rating Systems. It appears the rules are evolving (ex. Displacement Ventilation) as technologies and techniques evolve. And yet full credit for decoupled ventilation systems doesn’t currently exist and therefore may discourage designers and owner from investing in a system that often has higher first cost. We recommend and endorse this investment because of the excellent returns both in terms of dollars saved and carbon emissions reduced. We ask for your ruling to create an exception that allows credit for increased ventilation effectiveness and reduced ventilation rates (compared to multi-zone VAV systems) using a DOAS.

Can a four or five story residential building eligible to use the ENERGY STAR low-rise residential path in GIB Prerequisite 2: Minimum Building Energy Performance and GIB Credit 2: Building Energy Performance?

What is considered “hybrid” heating?