the activities of the occupants. Deep energy retrofit projects are an evidence to the fact that technology is available to set the thresholds of energy savings to a limit much higher than that achieved by a conventional retrofits. Deep energy retrofits achieve much greater energy efficiency by taking a whole-building approach, addressing many systems at once. It is most economical and convenient to take this approach on buildings with overall poor efficiency performance, with multiple systems nearing the end of useful life, and perhaps other reasons. Opportunity in Deep energy retrofit Deep energy retrofits and conventional energy retrofits both undertake different approaches and lead to varied outcomes. In scenarios where capital improvements are being looked forward to in an existing project deep energy retrofit is certainly an upper hand decision to create the most value out of investments in the long term. Deep energy retrofits can be well-timed to reap maximum benefits in such situations. Occupant behavior The overall success of the deep energy retrofit project also depends upon the inclusion of occupants in all the phases of the project. The phases include – project recruitment, project planning and during the use. Occupant behavior requires the project to focus on building owners’ needs and wants as much as the technical specifications. This ascertains actual performance, cost-effectiveness, willingness to progress from a design to an actual implementation, and occupant satisfaction. Also, evidence suggests that our building simulation models can become more accurate for a given house when we include actual operational information, such as thermostat set-points, appliance usage, etc. (Ingle et al., 2012). Over-time Retrofit Over-time retrofit is the implementation of a retrofit project which is planned in a step-by-step manner at intervals of time within a stipulated duration. Such an approach is usually sought for deep energy retrofits over an all-at-once approach to reduce the burden of large upfront costs and break it down into chunk of timely investments. Thus, over-time retrofit could at least be a viable option for a deep energy retrofit than going for conventional retrofits due to capital constraints. Research in the United Kingdom has demonstrated that retrofits carried out over-time can achieve levels of home performance equal to those achieved by all-at-once DERs (Fawcett, 2013; Fawcett, Killip, & Janda, 2014) and select projects have been successful in the U.S. (Less & Walker, 2014). Though such an approach has its own pros and cons which are