Electricity generation from intermittent renewable energy sources is expected to rise drastically, which may have profound implications for building design and operation. The authors propose a combined design and control optimization that takes intermittent renewable energy sources into account and adds two steps to the literature. First is the use of multiple temperature levels, which allows a more realistic representation of energy storage and conversion efficiencies. Second is the explicit inclusion of a simplified representation of the electricity generation side, which allows quantifying the value of flexible electricity demand. The proposed modeling framework is applied to nine scenarios for the electricity generation mix in Belgium. The results indicate that a hot water storage tank is not an attractive technology in the presented scenarios, altering the CO2 emissions less than 0.05 ton per building per year. This lowers the added value of modeling the temperature levels. The combination with the electricity generation system allows for a thorough assessment of the CO2 emissions. Within the boundary conditions of the case study, combining an air coupled heat pump, floor heating and PV panels reduces yearly CO2 emission up to 2 ton per building for an increase in annual cost below 350 EUR. (C) 2016 Elsevier B.V. All rights reserved.