Four people again attended this second meeting, the purpose of which is to share information among people interested in home and building automation. As previously, here are photos of the group’s collective memory along with my comments.

Fred told us first about a conference he had attended, organized and hosted by the Demontfort University in Leicester, England. The main subject of the conference was mainly user comfort, but according to Fred there’s a certain Cooper (or Copper, sorry if I got this wrong) who’s doing fairly detailed CFD simulations coupled with state-of-the-art thermal comfort models.

Friedrich, who joined us for the first time, told us about his research. He’s working on the non-visual aspects of indoor lighting, and on the important topic of spectral control on indoor lighting. I.e., he’s investigating whether “cold” fluorescent lights could have an impact on people’s feeling of well-being.

LESO has obviously been busy while I was away, as I learned that their sky scanner was being used again. It’s a highly reflective spherical mirror, laid flat on LESO’s roof, and a digital camera takes pictures of it from above. The mirror reflects the whole sky vault, so a computer that analyzes these pictures can then measure the sky luminance distribution. The sky can then be classified according to the standard CIE skies. (One ambition of LESO is to construct a catalog of representative skies for Lausanne, such as already exist for certain major cities.)

Friedrich is also using a head-mounted illuminance sensor that’s sensitive to the spectral quality of its incoming light. With this device, as I understood it, you can measure over a full day the quality of the eye-level light a person receives.

Very exciting work, I must say. I’m looking forward to seeing published papers.

The (non-invasive) automatic data acquisition on an inhabited building has always been a strong point of LESO. I’ve been myself somewhat involved in that effort, and one of my great regrets was not having had the time to work on a canonical data format for data recorded on a building. I personally believe there’s a need for this, because it is at the moment impossible for separate research groups to share their data without a major translation effort. It would have benefits for industry too, in the same way that a standard XML format for business activities helps the integration of legacy systems.

Someone raised a very interesting question at this point, the gist of which was “What’s wrong with Excel files?”. I have ranted against the use of Excel in academia before, but to these arguments I would add the following.

Scientific data in our field is almost always structured (i.e., not tree-like nor with arbitrary fields for each data item). So how you store your data boils essentially down to a flat file, a relational database (RDB), or a proprietary program (Excel being the obvious example, but Matlab or Igor Pro are others).

I dislike proprietary program being used in scientific work on the principle that any such work must be repeatable and verifiable. This is by definition impossible with a proprietary program whose source code nobody can inspect, and whose license costs might be a barrier.

Flat files or RDB are my own, humble, personal preference, with a slight bias towards RDBs for any long-running measurement campaign that can yield thousands or millions (as for LESO) datapoints. Flat files are the format of choice for analysis, since they can be freely shared among co-workers and colleagues and even published along with their peer-reviewed article.

Finally we talked about SUNtool, a simulation package to which LESO has contributed in the past but which has been plagued with difficulties. It appears that one commercial partner of that project has withdrawn its support, preventing the other partners from using their code. One ambition of LESO is now to start more-or-less from scratch and to develop a more open version of that tool.

That concluded our meeting, the next installment of which is tentatively scheduled for Moday September 1st.

On 4 July 2008 we held at LESO-PB the first of (hopefully) a series of meetings for people interested in home/building automation. The idea is to give people of widely different backgrounds a venue, time and opportunity to share, discuss and explore new ideas.

It was my pleasure to facilitate this meeting and although I did not hold any minutes, you can find here pictures of the notes I took during the meeting.

We started with introductions. It was great to have people from industry, academia and just plain hobbyists (like yours truly) interested in this subject. One thing we agreed on quite early was to discriminate between building automation (BA) and home automation (HA). BA will typically use completely different hardware and control algorithms than HA, so when a distinction needs to be made we agreed that HA is a subset of BA.

We started the discussion with two questions. 1) What is the state of BA today and 2) What is the role of building simulation in BA.

David started by telling us about the preliminary research he’s been doing for his PhD work at EPFL. He’s looking for building simulation software that would be modular enough to easily allow testing of different algorithms. This problem was similar to one I’d been working on during my own PhD so we talked a bit about the software I had used, SIMBAD, and in particular how it had been extended with Java/RMI to allow remote processes to connect to it.

One thing that Antoine stressed was the importance of building simulations for BA designers. The nature of the problem makes it impossible to run tests of control algorithms on real, occupied buildings and to get feedback in a timely manner. And the results would need to be compared to some base case anyway.

We talked a lot about the academic efforts in building simulation, especially the need for a good model of the users’ behaviour. The fact is that modern simulation packages do not have a good user model, and it is very difficult to estimate the errors being made on energy demand predictions.

On the other hand, it was very unclear whether such user models could be directly used by BA systems to anticipate user actions. Users usually act after some discomfort threshold has been exceeded, but any BA system should try to act before.

We briefly reviewed the user behaviour models that LESO had been working on for the past years, most notably Jessen’s occupancy model (the subject of his PhD thesis) and Fred’s window opening model.

Someone mentioned a research group in Zurich. I’m not 100% positive about this but I think this could be the group of Prof. Morari, with whom I had had a brief email exchange a couple of years ago.

Antoine stressed again the importance of reliability in BA systems. The reliability issue brought up a discussion on centralized vs distributed control systems.

We were shortly running out of time, so I asked the audience their recommendations for academic or trade publications of interest to BA. We concluded the meeting by regretting the lack of real innovation in BA, both academic and industrial, and observed that the big challenge facing building simulation today was the modelling of human factors and the urban environment.

Thanks to everyone who participated, and see you next time!