The well-known electrical analogy for thermal modelling is based on the observation that Fourier's equation for one dimensional heat transfer takes the same form as Ohm's law. This provides a system for creating and resolving complex heat transfer problems using an established set of physically-based equations. In this article, such a model is developed and evaluated for a four-floor modern university building. The model is represented in state space form for optimisation and simulation purposes. The electrical analogy is chosen so that the model can be extended and used for future research into distributed, demand-side control of multiple buildings on the university network, requiring a fast computation time. The estimation of occupancy, representing a significant internal heat source, is also investigated. Here, wifi usage and return CO2 data are combined in novel manner to improve the model response.