This article concerns fractional order control system design, with a focus on one method from the literature, namely Fractional order Generalised Predictive Control (FGPC). FGPC provides for an increase in the design flexibility of the well-known, conventional algorithm, Generalised Predictive Control (GPC). Both algorithms have a relatively straightforward implementation form, making them attractive to practitioners. This work represents one of the first implementations of FGPC design to a physical system in a laboratory context, namely the control of ventilation rate in a forced ventilation environmental test chamber. GPC and FGPC closed-loop responses are compared. Recommendations are developed for how to utilise the extra design coefficients in the fractional order case.