Building performance simulation

"Near-zero energy" buildings represent the next worldwide milestone for the construction sector since they are dwellings with very high energy performances.

This is important because we spend 90% of our time indoors and 40% of the primary energy consumption is spent on buildings. So, how do we get there?

Traditional technologies, such as ventilation heat recovery and envelope insulation, are not enough to reach this goal.

More sensitive technologies, such as demand-controlled ventilation, are needed, but they require user interactions so it's difficult to understand consequences.

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In this project, my team and I tried to answer this question with an analysis of a one-family building, located in Copenaghen, and how it can change its performances due to occupant behaviors.

We based our simulation on the methodology of this paper: "Influence of occupant's heating set-point preferences on indoor environmental quality and heating demand in residential buildings" [Fabi et al. 2013]

We compared the following three cases:

Rational behavior: users are reacting to the environment instantaneously. In reality, this means that a person is continuously turning on/off heaters when she feels unconformable. This is how most simulation programs are working.
Active behavior: users are changing their heating setpoint once a week.
Passive behavior: users are changing their heating setpoint once in a month.

To do so, we created different models on "IDA ICE 4.8". Then, we implemented these three behaviors as a new type of coordinate custom control strategy for heating devices.

As expected, we found, in our results, an important discrepancy between the rational simulation approach and the probabilistic one. Due to our focus on heating setpoint, it was involving mainly indoor temperature, energy consumption, and relative humidity.

An active user is the closest one to the optimal result thanks to their daily setpoint interactions.

In particular, we found that passive users tend to have lower setpoint in their houses and the worst indoor thermal comfort. Also, relative humidity is higher, which will damage the building structure. On one hand, they are consuming less energy but, on the other hand, what's more, important is that they are far away from the rational behavior which adds a degree of volatility, as can be seen from the table.

Since "near-zero energy" buildings can't have a wide margin of error, occupants must be constantly instructed to behave logically.