A passive solar house has south-facing windows that, in...

A passive solar house has south-facing windows that, in winter, admit solar energy at an average rate of $2.2 \mathrm{~kW}$. The house is well insulated, losing only $55 \mathrm{~W}$ for every ${ }^{\circ} \mathrm{C}$ temperature difference between inside and outside. What's the minimum outdoor temperature for which the house can maintain $21^{\circ} \mathrm{C}$ inside?

Key Concepts

Solar Energy as a Heat Source

Solar energy enters a building primarily through windows and other transparent elements, providing a free and renewable source of heat. The ability of solar radiation to deliver energy at a given rate is critical in offsetting the building’s losses and maintaining desired temperatures. Analyzing the solar input relative to losses enables the determination of conditions, such as the minimum outdoor temperature at which the system can remain effective.

Thermal Equilibrium and Energy Balance

Thermal equilibrium in a building context refers to the state where energy gains, such as those from solar radiation, exactly balance energy losses like those due to heat conduction. This energy balance determines the steady-state indoor temperature, making it a fundamental concept in assessing how design features and environmental conditions interact to maintain comfortable indoor climates.

Heat Transfer and Insulation

Heat transfer in a building occurs through mechanisms such as conduction, convection, and radiation. Insulation reduces the rate of heat loss by providing resistance to conductive heat flow between the interior and exterior environments. Understanding the rate of heat loss per degree of temperature difference is essential to evaluating a building’s thermal performance and energy demands.

Passive Solar Design

Passive solar design involves constructing buildings in such a way that they naturally collect, store, and distribute solar energy as heat during the winter months and reject heat during the summer. This design minimizes energy consumption by taking advantage of natural energy flows, without relying on mechanical heating or cooling systems, and is crucial in achieving energy-efficient building performance.

Transcript

Please give Ace some feedback