Thermal Mass


Significance of Thermal Mass
to a Passive Solar Design



Sunlight goes into south-facing windows and hit the thermal mass inside the house. There is the conversion from sunlight to heat energy that will take place which heat up both the materials and the air.

Commonly, on sunny days, the comfort of the solar heat can be maintained during the period of mid-morning up to the late afternoon. After the setting of the sun, it ends in supplying the home its heat.

Yet, a significant amount of heat has been kept and stored inside the thermal-mass. This heat will be released slowly in the passive rooms, maintaining the room to be comfortable especially during winter evenings.

A supplemental amount of heat is needed if the temperature falls below the comforting level. At night, the thermostat must be set back, so there will be a minimal need of back up heating. Heat losses in the outside of the house will be minimized if the energy inside the home is efficient.

The early morning hours are the coolest and at the same time, the hardest for the solar heating systems to give comfort. The thermal mass had normally provided all of its heat and the home had not yet heated because the sun has not risen up. At this period, supplemental heat is the only reliable source of heat for the homeowners.

Thermal mass is needed in sun spaces for it to remain comfortable just like other spaces containing lots of south glass. The design of a sun space is a living space that must have enough thermal-mass with the combination of masonry north wall and cement floor.

Sun spaces are always subjected to extreme conditions. If there is no enough thermal mass in the sun space, it will not be a comfortable equally as the sitting room. Nevertheless, it can still function as a solar-heated entrance.

As long as there is enough air movement between the sun space and the house, it will not overheat. In the winter, it will function as a warm entryway. It must be secured against leakage from the living space so that the sun space will not either heat or cool the entire house too much.

The location of the thermal around the house can provide enough heat when specific parts of the house started to cool. This part of the house that cools quickly at night needs an increased amount of thermal-mass to be placed in these places.

Commonly, windows that are facing the north are the main areas of heat losses because they are facing to the shaded and cooler areas of the location. Indeed, when the thermal-mass is placed near these windows facing north, it has the tendency of keeping the space more consistent in temperature.

In the same way, if it is placed under the windows that are facing the south, there is a slowing down of the heat loss out of the window. The best application of thermal-mass is the time when the sunlight falls on its surface.

A tiled floor is open to longer hours of sunlight from the windows facing the south as the path of the sunlight moves throughout the floor. This is the main reason why tiled floors that are placed on a thick concrete slab has good performance because they obtain sunlight heating on the large surface and later at night, they re-radiate , providing a substantial source of heat.

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