Between December, 2009 and December, 2012 42 deep energy retrofit (DER) projects were completed through a DER pilot program sponsored by National Grid and conducted in Massachusetts and Rhode Island. 37 of these projects were comprehensive retrofits while 5 were partial DERs, meaning that high performance retrofit was implemented for a single major enclosure component or a limited number of majorenclosure components. The 42 DER projects represent 60 units of housing. The comprehensive projects all implemented a consistent 'package' of measures in terms of the performance targeted for major building components. Projects exhibited some variations in the approach to implementing the retrofit package. Pre- and post-retrofit air leakage measurements were performed for each of the projects.Each project also reported information about project costs including identification of energy-related costs. Post-retrofit energy-use data was obtained for 29 of the DER projects. Post-retrofit energy use was analyzed based on the net energy used by the DER project regardless of whether the energy was generated on site or delivered to the site. Homeowner surveys were returned by 12 of the pilotparticipants. Based on the community experience, this DER package is expected to result in yearly source energy use near 110 MMBtu/year or approximately 40% below the Northeast regional average. Larger to medium sized homes that successful implement these retrofits can be expected to achieve source EUI that is comparable to Passive House targets for new construction. The community of DERprojects show post-retrofit airtightness below 1.5 ACH50 to be eminently achievable.