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Daylight Savings Time in TRACE 700 and eQUEST

Mar 11, 2013

Good old Daylight savings time is officially in play. For many of you reading this, you may never have heard of it, but it's something we do in much of the United States, Canada, and Europe, as well as other parts of the world. Basically, we move our clocks an hour forward for about half of the year.

The history of daylight savings time is actually pretty interesting, and recently, it was moved into March because it was deemed to save significant amounts of energy. (Culturally, more people stay up later than get up early, therefore - less lights are used!).

In any case, this reminded me of a common question: How do I model Daylight savings time in TRACE 700 or eQUEST

It's really easy!

To make the change in TRACE 700

Go to the Actions Menu
Select "Change Load Parameters"
In the lower right, select the Daylight savings time period (this would be March-November for many regions).
NOTE - the "Summer Period" is unrelated to daylight savings time, but it is easy to mistake. However, if you made the mistake of selecting March-November for the summer period, the impact would be minor!

To make the Change in eQUEST:

Daylight Savings time is automatically implemented in eQUEST. It is not sufficiently easy to change the exact months.

It is "On" by default, which works for much of eQUEST's market, but the large international audience may want to know how to turn it off:

Go to the "Project and Site Module"
Right click on "Site Data" and select "Properties
On the first tab, you can simply set "Daylight savings time" to "No"

Good luck with Daylight Savings time. Please note that it has a significant impact when you model Daylighting (daylight harvesting), but it also has an impact on your cooling and heating profiles!

Bonus LEED Points by Simple Math

Feb 2, 2012

LEED Points Logo

Let's cut straight to it:

LEED background information:

LEED energy models have a default requirement that process loads and receptacles are 25% of the baseline building costs. The total cost must be identical in the proposed LEED model.

However, this assumption is based on a standard office building. Thus, if the process loads and receptacles are designed and documented (think spreadsheets, or even a basic description), one can use the actual designed loads. This can yield free leed points, bascially LEED plus a little math gets you 2 valuable LEED points.

....LEED + Math = 2 Points!

Example LEED Case Study:

Let's consider a building that has 31% savings on the proposed building over 90.1-2007 building:

Let's say the Baseline utilities are $100,000 annuallu, of which $25,000 is from misc equipment ($75,000 from everything else). At 31% savings, the Proposed building would be $69,000 annually - of which $25,000 is from misc equipment (since by default, it must equal the baseline)

If instead, someone took the time to do it, and the misc loads were documented and that made the price equal to $15,000 in the baseline model, the revised savings are:

Baseline:

$75,000 (everything else) + $15,000 = $90,000

Proposed:

$44,000 (everything else) + $15,000 = $59,000

Final percent savings:

(1 - 59/90)*100% = 34.4% savings

With the extra 3.4% savings. This math yields 2 additional LEED points!

While there are other end effects of the misc load that effect cooling, lower documented loads almost always increase the savings. This is greatly increased if the proposed misc loads can show documented savings over industry standards (ie energy star, but the savings must also be documented)

So why do people assume 25% on misc loads so often?

The receptacles are hard to predict and it's tedious to count all items room by room. However, most projects have some level of detail in the receptacle loads and a little extra effort up front will pay dividends. In fact, if you can make a simple explanation, they will likely accept it. The bottom line is:

NEVER arbitrarily increase receptacles to 25%!

Half Glassed - TRACE 700 & LEED glass percentage?

Jan 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%

In Alternative 2:

Lets say you tried to enter the same percentage and thus entered 83.3% glass on all walls (claiming the value from the report)

The report will say 100%

When you ENTER percent glass, TRACE uses the Gross wall area to calculate the total square footage of glass (in this case .83*1000).

But, in the Building area report, it calculates the Percent glass differently.

(.83*1000)/(1000-400) which is >100% so it comes out to 100% glass.

Kind of strange, you have a WWR of 50%, and you can somehow end up with 100% glass! This comes from an inconsistency in the definition of glass percentage (in your entered values, it is based on gross wall area, in the reports it is based on True wall area).

View the attached file to illustrate the example.

How do you calculate the Window wall ratio or WWR for LEED?

LEED requires that you use the gross wall area, defined by 90.1 users manual as:

Gross wall area = (opaque wall area + opaque door area + window area).

In this case that means it is 10*100 or 1000 square feet.

So, the WWR for this is 500/1000 or 50% (which of course is too much for LEED and you would need to reset to 40%, which is why you really need to understand this!

What's the solution:

Don't use openings for doors (maybe add another wall instead)
Show a separate calculation, when reporting glass area to LEED
Use the component Tree view and a spreadsheet to show the WWR as defined by LEED.

Another glass percentage tip:

If you are very close to the limit of the percentage of glass, do not forget to include the "slab thickness" in your calculations. You can either add this to your wall height, or implement it in a side calcultion. (If you consider a 6" slab and a 10 foot wall, it can make a difference of 5%)

Counter-Intuitive Wall Insulation Energy Study

Oct 7, 2011

A while ago, energy-models.com published a blog, "Is insulation the best energy saver?" and illustrated the number of hours where high R-values may increase energy. People may argue, "that's what an economizer is for!" In my opinion, that of course is a good argument, but I have talked to too many people who have asked, "Why does my energy go up with increased wall insulation?"

To test this scenario, we looked to our good friend eQUEST. We built a simple building and tested it over a range of climate zones, and a range of R-values. In order to "normalize" the data, we compared everything to R-9 insulation (which is a pretty low R-value). We also made a number of assumptions:

L shaped Office building (100,000 sq ft)
Only Wall insulation was evaluated
DB economizer set to 65 degrees F
43 percent glass (glass stayed constant at triple low-E to minimize effect of glass)
Medium high internal loads (1.5 w/sq ft lights, 2 w/sq ft plug loads)
12 hour occupancy per day, 7 days a week
76/70 F cooling/heating setpoints (82/64 unnoccupied)
No change in infiltration was considered
Different building orientations were evaluated without change to normalized results
10 cents/kw-hr and 1.00/therm were used with no demand charges
Only climate zones A were evaluated, though results should be similar for B

The results were very surprising given that insulation only showed an increase in savings for the extreme climates: climate zones 1, 6, 7 and 8.

For climate zones 3A and 4A, more insulation actually yielded AN INCREASE in cost (even with the economizer). Most interestingly, for climate zone 4, an obvious "sweet spot" was displayed.

Check out the results for yourself:

Google Visualization API Sample

Miami, FL	1A
Orlando, FL	2A
Dallas, TX	3A
Lexington, KY	4A
Chicago, IL	5A
Fargo, ND	7A

It should be noted that a number of other locations were tested at each climate zone and the results were surprisingly consistent. The final data comes from the listed cities.

eQUEST Space ReNamer In-Depth

Sep 12, 2011

We're excited to release our new space renaming tool for eQUEST. The following is an in-depth description on how to use the tool.

Start eQUEST and run through the wizards (or however you set up a file)
Enter Detailed Mode
Go to the "Building Shell Module"
Rename your SPACESOnly.

Use the spreadsheet view!

Don't Rename the Plenum Spaces! Don't Rename the zones!
Save your file in eQUEST
Go to the energy-models.com Space Renamer:
Navigate to your .inp file
Select "open" and then "rename spaces" (ie in the screenshot below)
Download your modified file by clicking the link, it will download automatically
Backup your original *.inp file
Rename the modified file to the original name and replace in your project folder (recommend that you move the original .inp, and replace)

You will now have a file with the space's corresponding plenums and zones renamed!

The Real Effect of Lighting on Energy and LEED points

Aug 16, 2011

EAc1 LEED points can't fall entirely on the back of the MEP!

I've probably seen as many LEED files as most LEED reviewers. What blows my mind is that most of the files I have seen save very little in lighting, even though lighting is often 25% of the building energy costs. In my opinion, this is a result of Architects and firms who, let's face it, are too set in their ways to change their designs. (Either that, or it's just plain laziness). Perhaps, I am being harsh and they simply don’t understand the huge impact lighting has on LEED points. So, I’m going to spell it out mathematically, but first let’s see how a typical conversation goes:

"We have a design that is going to save 30% on energy costs annually. The HVAC has an improvement of 35% over the 90.1-2007 baseline, and we are using such and such.."

…..But then, I look at the lighting and see that it is designed at 1.2 watts/sq ft compared to a baseline building at 1.3 w/sq ft .

Now if you're asking, "what's wrong with this?"- I want to ask you, "What's wrong with you and why are you reading my blog?" Okay, maybe I'm being harsh again but it's really simple math and I shouldn't need to explain it in depth. The truth is that lights are one of the best ways to earn LEED points.

Here's a rule of thumb for LEED buildings:

Whatever your intended net savings on LEED is, your lighting design should save that percentage against the whole building method. (for buildings where lights are the typical 15-25% of savings)

Example:

Target savings: 30%

Whole building method lighting: 1.2 w/sq ft

Designed lighting (after 10% credit for sensors) equal or less than: 1.2 *.7 = .84 w/sq ft

Now, I see a lot of jaws drop at this, but that's only because they have been designing buildings the same way for 30 years. The message from LEED is that things need to change. The work that will go into this design will save days and maybe weeks of backtracking in the design when you find that it’s mathematically impossible to save 30% on your project without saving more in your lighting. That said, let’s take a look at the TRUE impact of lights on LEED points

What is the true extent of designing highly efficient lighting systems?

Let's assume we are comparing to a baseline building that uses 1.3 w/sq ft on (whole building area method) and let's assume the whole building design averages to .84 w/sq ft. What is the savings on this? Well, most people will say, "that's easy, .46/1.3 or 35%"

However, most people forget about the additional savings that comes from lights, especially in a cooling and in heating when the heat is non-electric. Remember, lights give off heat and therefore increase the amount of cooling energy (compressor, fan, and heat rejection).

So, what's the real saving:

Let's assume a VAV system and that lights save on the compressor, fan, and heat rejection with an overall EER of 13.65 (~COP of 4)

.46 w/sq ft = .46 w/sq ft immediate lighting savings

.46 w/sq ft * 1/4 = .115 w/sq ft compressor/fan savings

Total: .575 w/sq ft actual savings in cooling mode

So, a 35% savings on the lighting yields an effective savings of nearly 45%.

Yeah, but don't the lights provide "free" heat in heating mode?

Let's assume there is gas heat, electricity costs $ .10 kw-hr, and gas costs $1.00/therm (so we will do this in costs). We will also assume a 90% efficiency in heating equipment and 4000 hours of operation.

Using the energy-modeler's unit converter, we find that 1 therm = 29.3 kw-hr

.46 w/sq ft *$.00010/w-hr*4000hrs = $.184 /sq ft immediate lighting savings

.46 w/sq ft /29300 w/thm*1/.9*4000hrs = -$.070 /sq ft addtnl heating required

Net savings of $.114/sq ft in heating mode

So, yes, there is an offset in heating mode but there is still substantial savings as long as the heating is provided using low cost fossil fuels (relative to electricity) or if heat pumps are used in heating mode.

Furthermore, most commercial buildings have a significant amount of cooling required. Remember, even in economizer mode, additional cooling means more fan energy.

Several sets of data were simulated in eQUEST to see how various cities saved. As predicted, cities with greater cooling showed the greatest savings per watt of lighting saved. It was surprising that even Fairbanks, Alaska had similar savings to climates like Miami. If additional effects, such as summer demand charges are considered, the savings would further increase!

See the calculated data for yourself:

Lighting power cost savings by city
Google Visualization API Sample

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