# Publications

Here I list academic papers related to building research that I have authored.

### A simplified daylight model suitable for daylight controllers

#### David Lindelöf

Solar Energy Journal (submitted)

This paper describes a simplified daylight model suitable for low-power embedded daylight controllers. For a given blinds’ settings, it models indoor illuminances as a linear combination of outdoor global illuminance and outdoor diffuse illuminance, for a given position of the sun. A controller that implement this model needs to persistently save previous measurements of illuminance, blinds’ settings and sun positions, and this data is used to model current illuminance values. We have validated this model against a Radiance model, and also implemented a daylight controller that adjusts the horizontal workplane illuminance to a given setpoint with this model. This controller has been validated against a building simulator.

The paper’s full, pre-print text is available here.

### Bayesian estimation of visual discomfort

#### David Lindelöf and Nicolas Morel

Building Research and Information (in press)

This article proposes a method to objectively estimate the visual discomfort in small office rooms as a function of the illuminance on one or more location. Expressed as a visual discomfort probability, it is based on an analysis of the past history of the user’s interactions with the blinds’ and lighting controls. A bayesian formalism is applied to infer the probability that any illuminance distribution should be considered by the user as visually uncomfortable.

We have applied this method on the interactions of the LESO experimental building’s users and derived a discomfort probability as function of the horizontal workplane illuminance. This discomfort probability is very high (0.5–1.0) for an illuminance below 200 lx; it reaches a global minimum (about 0.3) at 500 lx, and increases then gradually for larger illuminances until it reaches 1.0 again close to 3000 lx.

The paper’s full, pre-print text is available here. The source code distribution used to produce the plots of the paper is available here.

### A field investigation of the intermediate light switching by users

#### David Lindelöf and Nicolas Morel

Energy & Buildings, 38 (7), p.790-801, Jul 2006

doi:10.1016/j.enbuild.2006.03.003

This paper describes how data collected during a continuously running data acquisition program on the LESO building in Lausanne, Switzerland, was used to measure the *intermediate light switch probability* by users as a function of current illuminance levels, i.e. the probability for a given timestep that the user will switch on or off the electric lighting, excluding such actions that happen upon user entry to or exit from the office. We assume such a probability to be independent of the user’s history and further derive some theoretical consequences of this postulate. In particular, we show how a history-less user leads naturally to patterns of behaviour already observed in real buildings.

The paper’s full, pre-print text is available here.