Specifications include, but are not limited to: 2.1.3.1 Adequate survey data to establish allowances for HA-purchased utilities for each dwelling unit category and unit size. 2.1.3.2 Recommended sources of data include, but are not limited to: 2.1.3.2.1 Consumption information from the HA, HA residents, and/or utility suppliers; 2.1.3.2.2 Utilizing heat loss/heat gain engineering calculations based upon the thermal characteristics of each type of building and unit, and consideration of the standard of living within the community; 2.1.3.2.3 Previously conducted energy audits; 2.1.3.2.4 Physical inspections of representative units; 2.1.3.2.5 Building plans and modernization documentation; 2.1.3.2.6 Interviews of residents to obtain insight into energy usage; 2.1.3.2.7 Interviews of maintenance personnel and project managers to gain understanding of HVAC equipment and how housing facilities are used by residents.