Daylighting Beyond LEED Part 2

Part 2 is the response to the LEED CIR posted in Part 1

First let me explain the title. The words "Beyond LEED" are not meant to criticize the LEED rating system but only to critically evaluate the LEED analysis requirements against more advanced analysis capabilities available. Specifically, the use of dynamic simulations which takes annual weather data into account may eventually replace static simulations. However, since the majority of this post is about achieving LEED, maybe we should first focus on getting that right. For those going through the process for the first time, the following USGBC clarification points from their CIR ruling may be helpful.

Ruling
The applicant has submitted a multi-point question regarding guidance related to the use of analysis software for the documentation of the daylight distribution. The ruling is provided in order of the questions asked.

1. While there are no specific defaults that have been established by any modeling protocols for daylight simulation, it is reasonable to assume reflectance values similar to those used for calculating lighting fixture coefficients. For example, typical reflectance values could be 50% for walls, 20% for the floor and 80% for the ceiling. If known, actual values must be used.

2. Only the analysis grid is required. There is no need to model the actual work plane.

3. While this CIR cannot provide any specific rules for selection of the sky model to be used, both methodologies are acceptable as long as the applicant submits a narrative explaining the methodology in the submittal.

4. See item 5 below

5.
a. The assumption made is correct. All area above the threshold can be counted, as long as these areas separately defined.
b. Software analysis from grid points is acceptable, as long as the grid points do not fall in walls, columns and other elements that may return a null value and skew results. Adjustments and additional post processing calculations may be necessary to exclude these instances. Secondly, various simulation programs draw foot-candle or daylight factor iso-contours. This is the best way to understand which areas of a space meet or exceed the threshold. Again, adjustments may be necessary.

While this ruling provides guidance to the applicant, it should be noted that there are no set modeling guidelines available for daylight analysis. For the purposes of this credit, it is expected that the person(s) responsible for the analysis have enough experience to make the most appropriate determination of the daylight analysis methodology.

SketchUp Virtual Environment

The green software industry moves forward yet again with the recent announcement of an IES plug-in for Google SketchUp. Similar to the Revit Architecture plug-in IES now offers their VE-Ware, their sustainability toolkit and a direct link into Virtual Environment, one of the most robust, engineering grade analysis programs in the industry.

At the basic level this means that with a free version of SketchUp and a free VE-Ware plug-in, anyone across the globe can design a building or a home and evaluate the energy performance while tracking carbon emissions against the 2030 challenge. For those like myself who are passionate about change, we warmly welcome the opening up of the competition to any clever person owning a computer.

At the professional level this opens up these free tools to those modeling accurately in any non-BIM tools which can be exported into SketchUp (Rhino, 3DS Max, etc.). In essence, any firm using Revit in conjunction with other design tools now has the ability to track carbon at every stage of every project…with a free plug-in.

Sketchup Model...

IES import

As a personal opinion, for those who have been following earlier blogs I can say that IES has taken the lead among energy modeling tools. http://greenbimnetwork.blogspot.com/2008/06/engineer-takes-lead.html “But perhaps more importantly this software will be able to reuse architectural design models, architectural construction models, and will promote interoperability by cleanly exchanging data between all design and analysis platforms.” While IES is not yet fully interoperable with all platforms, they have swung the door wide open.