Heat storage is another area of hybrid system design that has great potential for growth in the market, and even greater potentials for efficiencies and overall effectiveness of a structure. There are two main ways of capturing and storing heat, the thermal heat capacity and latent heat capacity. The first is fairly simple; objects with mass can absorb heat and get hot. Asphalt on a summer day is a great example of this, a large thermal mass than can absorb heat and store it to release it later in the day when it is cooler out. Houses currently use things like trombe walls or large stone fireplaces to store heat from one source, and release it into the house when it’s cooler outside later.