Increasing the thermal mass of a building and installing a photovoltaic system would help with:

Increasing the thermal mass of a building and installing a photovoltaic system effectively contributes to reducing energy demand while simultaneously increasing the use of renewable energy sources.

Thermal mass refers to the ability of a building material to absorb, store, and later release heat. By having higher thermal mass, a structure can better regulate indoor temperatures by absorbing excess heat during hot periods and releasing it during cooler times. This leads to a reduced need for mechanical heating and cooling systems, thereby lowering overall energy demand.

On the other hand, a photovoltaic system harnesses solar energy, converting it into electricity. This directly increases the share of renewable energy used within a building's energy mix, making it more sustainable. By combining these two strategies, the building can operate more efficiently and decrease its reliance on non-renewable energy sources, thus achieving a comprehensive approach to energy management and sustainability.

The other options, such as maximizing indoor air quality, enhancing acoustic performance, and improving natural lighting, are not directly tied to the effects of thermal mass and photovoltaic systems.