The energy consumption and indoor climate of two aged conjugal households in a cold climatic region of Japan were measured. Both houses had low thermal insulation because they were built in the 1960s and 1970s. As a result, the annual energy consumption from August 2008 to July 2009 for both households was around 45 GJ/a, with the monthly energy consumption for both houses fluctuating between 2 and 7 GJ/month. The annual energy consumption of the aged conjugal households was 20% less than that reported in reference data, because the energy consumption was lower for space heating in one house and for hot water supply in the other. In addition, experiments on lifestyle modifications for energy conservation were carried out, and a questionnaire survey was conducted regarding the frequency of action for implementing energy conservation measures in winter, spring and summer; the consequent energy savings of these lifestyle modifications were analyzed.