Our paper presents findings from in-depth monitoring of two single-family "Net Zero Energy Homes" (NZEH) in Massachusetts, begun in July and October 2010 respectively. It concentrates on the cooling period 2010. In both buildings, we measured the electric energy consumption at the circuit level. In addition, we measured parameters related to indoor comfort and indoor air quality on seasonal test series. Based on these measurements, we generated average daily electric load profiles during a large portion of the cooling season. We also used indoor temperature and relative humidity measurement to evaluate thermal comfort based on static and an adaptive comfort models. Finally, we used CO2concentration measurements as an indicator for indoor air quality (IAQ) and to assess the sufficiency of air exchange rates.