CJ's profile - activity

Hi everyone. Regardless of modeling software, I am curious to know what assumptions you make when modeling blinds, when all you know is that there are blinds.

This is with the consideration that the occupants will not be actively moving blinds up and down as required. Ideally, you would model using a schedule/s that makes blinds open / close with varying degrees in response to direct solar radiation, or another criteria pertinent to your case. In eQUEST, you can add a sun control probability %, which basically says how often your occupants will demonstrate conscious behavior. Other programs likely have similar input.

So, what is your usual basic input for the following, when detailed info is unavailable:

1. Percent of occupied hours when blinds are down?
2. When down, percent of blinds closed?
3. Points 1 and 2 above, but for unoccupied hours.

I realize that my subject line is a bit more broad. You are welcome to make this a general discussion on modeling blinds / interior operable shades / good old window shutters etc, trade-offs, pros and cons of methods. Thank you.

Okay, turns out you cannot have hourly values in a user expression. Exploring the option of using an 8760 shading schedule as a workaround to model this.

About the 34' high gym ceiling...I think you might want to avoid using thumb rules on that one, instead a short conversation with the lighting designer if possible. Do the windows start at floor level, or at least at low sill height? Or are they clerestory windows, with sill height of 15'? If the windows are placed high up, then the area near the wall will get less natural light most of the year, and the daylighting zone will get pushed inwards, like an island. Those type of questions will help distill the daylighting zone modeling criteria for you.

Also, about the ceiling height based daylighting zone depth...that thumb rule considers the possibility of considerable light first being reflected on to the ceiling, which then can be re-reflected into deeper space. Thus, check whether you have light shelves, or other daylight redirection devices in place, or the exterior ground being very reflective (then you gotta think about direct glare as well btw) etc.

For a good primer on daylighting thumb rules, see this 2009 Harvard presentation 'Daylighting, Rules of thumb'.

Hope this helps.

Thanks Neal. I see how this works now.

True. I am aware of eQUEST's native glazing switch capability based on the criteria you listed. But if you had to vary an eQUEST input by the hour like I described, how would you? I am open to ideas beyond the 2 options I could think of.

Thanks for responding.

I am working on a study project, and looking for ways to model glazing switch in eQUEST explicitly, meaning, forcing eQUEST to do one of the following:

Option 1: Switch GLASS-TYPE (4 available) based on the hour of the year, and not use eQUEST's built-in glazing switch functionality.

Option 2: Use the Layer-By-Layer specification method, and switch one layer based on the hour of the year.

I imagine that Option 1 is achievable with a user expression input for GLASS-TYPE, something along the lines of:

Hour 1: "Glass A", Hour 2: "Glass B" ... Hour 8760: "Glass D"

For Option 2, we would also need a similar user expression input for the window layer being switched (such as Hour 1: Layer 1...Hour 8760: Layer 4).

Part of what I am trying to look at is the simulation runtimes in these options, besides the effect on annual results.

I'd really appreciate if someone could help with writing user expressions for these 2 options. Once I have the format/s for them, I can automate it quickly in Excel and then back into eQUEST.