A home in Toronto recently re-constructed with Structural Insulated Panels (SIPs) was analyzed and an energy simulation using HOT2000 and PHPP was created based on the current state of the house. The simulations were used to determine compliance with the Canadian R-2000 standard and the Passive House standard. The building met the R-2000 standard in its current state. Further analysis was required in order to determine design changes that may be made to achieve Passive House. This research determined the applicability of SIPs to achieve these standards in the context of the subject home. Through the redesign of the building enclosure assemblies and the elimination of the thermal bridges through the envelope, the Passive House standard was achieved using a double wall stud SIP. A number of design changes were also required including better performing windows and HRV as well as the addition of glazing to the south façade and removal of glazing on other facades. These design changes were then applied to HOT2000 and it was found that the Passive House building achieved an energy savings of 60% compared to the R-2000 standard baseline.