[esp-r] Re: Proposed development of window shading models

[blomanow at engmail.uwaterloo.ca]

Unfortunately I don't think anyone from our group will be able to join the 
conference next week, but I am preparing a document to summarize the 
capabilities of our shading models in a little more detail as well as some of 
the implementation issues. I will forward it by the end of this week. Perhaps 
this can be useful for discussion at the conference.  

Some of the issues put forward will definitely be challenging, for example the 
issue of treating the inside blind as a separate surface in the zone, or 
lumping it with the glazing construction. One can appreciate the complexity of 
the longwave exchange between the glazing behind the blind and the rest of the 
zone surfaces. 

As I mentioned before, the project is in the early stages so we don't have all 
the interfacing issues worked out yet. I would like to point out that althought 
our capabilities may be similar in scope to WIS or WINDOW 6, our models are 
geared toward energy simulation. Adding the treatment of complex shading 
systems into ESP-r, as opposed to importing data from WINDOW into the optical 
database, would be beneficial especially for developing real-time blind 
control.  
   
Best Regards,

Bart Lomanowski


Quoting Jon Hand <jon at esru.strath.ac.uk>:

> 
> Re: email for window shading systems....
> 
> There are several issues that would be useful to discuss:
> 
> a) Blinds imply the possibility of either user or automated control
>     actions and there are several people in the development community
>     who have an interest in enabling better control of blinds and other
>     aspects of optical properties.  
> 
>     Currently optical controls are held in the zone tmc file and options
>     for what can be sensed and what can be actuated are frustratingly
>     different than they are for other zone controls.  And when surfaces
>     are added or deleted from a zone these contols sometimes fail.
> 
> b)  Between-glass blinds are one of the simpler cases. Traditionally
>     one adds a layer within the construction and associates appropriate
>     optical properties (e.g. a roller blind). The solution technique tracks
>     the solar radiation absorbed by the blind layer and it would be useful
>     to discuss whether the proposal is to extend this approach.
> 
>     If blinds are within the room and the blinds change physically what
> should the
>     rest of the solution domain recognise as the surface or surfaces
>     that make up the blind?  Are the blinds aggregated within the surface
> that
>     is transparent or are they explicit surface(s) within the room with full
>     interaction with the surrounding zone.
> 
>     When blinds get hot one should observe long wave exchanges as well at 
>     the solar band distributions.  In the proposal what, specifically is it
> that
>     the other surfaces interact with for the various flux exchanges?
> 
>     After the simulation has run users might wish to enquire as to the state
> of the
>     blind.  And how does one report on the energy balance?   What
> blind-related
>     information might be useful to record for later analysis?
> 
> c) Blinds on the outside of the building are also delightfully
>     complex in their physics - one might expect exterior blinds
>     to impact both the near-building air temperature and the short-wave
>     and long wave environment at the facade.  Some work was done
>     in other research projects and whether what was learned elsewhere
>     can be incorportated would be useful to talk about.  How would
>     the proposal interact with the current shading analysis tool?
> 
> d) How is the proposed method different than what is being carried
>     out in WIS?  Window 6 from California includes some blind descriptors
>     so what can be learned from these other approaches? 
> 
>     Is this a replacement for externally generated optical
>     properties sets?  Is this proposal to work in conjunction with
>     current optical properties within esp-r or to have an alternative
>     path or as a replacement?
> 
> e) Blind geometry and possible rotations and transforms are currently 
>     not included as descriptive fields in the model files (only the
> aggregate
>     change in optical properties).  Is the proposal to re-form the matrix
>     as required to account for a different geometry within the zone?
> 
> f) Those looking at designs such as double skin facades will probably
>    bring up the issue of treatement and control of blinds within partitions.
> 
> g) Facade engineers will probably be interested in how actions of
>     blinds create different resistences to air flows within rooms and
>     in the case of blinds suspended within double skin facades.
> 
> h) The current optical properties database probably needs to evolve
>     to support the description of blinds (actually lots of things need
>     to evolve in terms of optical properties). Horizontal and vertical blinds
> will
>     introduce direct-to-diffuse flux optical issues that are covered by the
>     calculations in WIS - similar ideas are probably needed.
>   
> It would be great if materials could be made available for use in
> discussions at the developers conference later this month.  Of course
> it someone from Canada could come along to the conference and
> join in the discussions that would be even better!
> 
> -Jon Hand
> 
> -----Original Message-----
> From: esp-r-bounces at lists.strath.ac.uk on behalf of Bart Lomanowski
> Sent: Mon 3/12/2007 3:29 AM
> To: esp-r at lists.strath.ac.uk
> Subject: [esp-r]  Proposed development of window shading models
>  
> Hello All,
> 
> In response to Jon's reply...
> 
> I am a Master's student at the Solar Thermal Research Lab at the University
> of 
> Waterloo. Our group has developed window shading models focusing on the 
> accurate treatment of venetian blinds in glazing systems. 
> 
> The models essentially extend a standard center-glass glazing analysis to add
> 
> venetian blinds of arbitrary geometry, slat angle and position within the 
> glazing system. The analysis is based on calculating spatially averaged, or 
> effective solar optical and longwave properties for a shading layer given a 
> specific geometry and slat surface reflectance. A multi-layer solar optical 
> analysis determines the absorbed, transmitted and reflected components of 
> incident beam (off-normal) and diffuse solar radiation. Next, a heat transfer
> 
> analysis, including the absorbed solar radiation terms, determines all the 
> radiative and convective fluxes and layer temperatures. A convection 
> correlation has been developed for a between-the-panes venetian blind. 
> 
> Proposed ESP-r development:
> The development, still in the early stages, aims to create an "advanced
> glazing 
> systems" facility giving the user the freedom to specify any glazing/shading
> 
> arrangement . The optical properties for glazing/shading systems would be 
> calculated based on the insolation data per time-step, allowing for accurate
> 
> solar energy accounting. Convective and radiative heat transfer across air
> gaps 
> would be treated in more detail than the current air gap resistance 
> approach.    
> 
> These models will pave way for the development of intelligent automated blind
> 
> systems. 
> 
> The method of implementation is still in the early stages so there is still 
> uncertainty about code interventions at this time. I anticipate that the 
> subroutines MZSLGN, MZCOE1 and MZSETU will require extensive work, however,
> the 
> plan is to create new subroutines for handling advanced glazing systems.
> 
> I look forward to discussions on the subject.
> 
> Regards,
> Bart Lomanowski
> 
> 
> 
> 
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