# tracewindu's blog

## Half Glassed - TRACE 700 & LEED glass percentage?

Posted on: January 27, 2012

So, you need to implement percent glass calculations in LEED? This has proved a bit confusing since the additions of doors to the "openings" and I think it requires explanation.

What's the relevance? Well, if you are near 40% glass, or say you're half glassed - this could make or break your model:

Here's the reason why: The TRACE 700 reports calculate the glass based on the Wall area only (and not the gross wall area, which includes Opaques doors). So if you have doors, your TRACE reports may over-estimate the percent glass. Let's take an example of a building that is "Half-glassed":

## Let's take an example:

### Alternative 1:

Wall 10 x 100 feet (1000 sq feet)

Window 5 x 100 feet (500 sq feet)

Opaque Door 40 x 10 feet  (400 sq feet)

Building Area Report: 83.3% window.

Which is 500/(1000 - 400). In other words. It isn't accounting for the door area or the "gross wall aread". The window to wall ratio is actually 50%

## ASHRAE Wisdom from a LEED Jedi

Posted on: August 12, 2011

## ASHRAE Standard 90.1, Appendix G Fan Power Calculations

It’s safe to say that there’s a solid ten (or more) requirements in Appendix G that engineers, energy modelers, and rating authority reviewers consistently trip over. If I had \$100 for every conversation I’ve had about correctly calculating the baseline system fan power per Appendix G, I’d be sipping a drink with an umbrella on an island somewhere.

In this first installment of “Wisdom from a TRACE Jedi” we’ll be discussing the baseline supply fan power calculations when exhaust fans (toilet, garage, etc.) are involved. The ECB subcommittee of 90.1 published a formal interpretation ruling on just this topic in the summer of 2010 and thus will be the basis of our discussion. The interpretation ruling was specifically written in regards to 90.1-2004 though the logic and foundation of the ruling does still apply to 90.1-2007 and 90.1-2010.

### 1. Should Table G3.1 No. 12 be used for determining fan power from equipment such as toilet, garage, or general exhaust fans?

No – If the space use classification for a zone or thermal block is semi-heated or unconditioned then hat space’s fan power from equipment such as toilet, garage, or general exhaust fans would be the same between the baseline and proposed per Table G3.1 No. 12. If the space use classification for a zone or thermal block is conditioned then G3.1.2.9 is used to determine baseline system total fan power.