Drill:

How many times would an average car’s tires turn during a drive from downtown Baltimore to downtown Washington, DC? [What would you need to know? Explain your reasoning and show your work.]

(Est. Distance, B’more to DC)/Tire Circumference=# of Rotations

(40 miles)(5280 ft/mile)/ (2p*1 ft) = 33,614 Rotations

Passive Solar Energy

Essential Questions

What is passive solar energy and how can it be used?

Passive Solar Energy

The capture and use of solar energy w/o the aid of any moving mechanical systems. Heating Homes

Cooking

Roman Bathhouses Anasazi Pueblos Modern Solar HomeSolar Ovens

Solar Oven Design:

Solar Box Cookers An insulating box with a glass cover to allow visible radiation to enter;

solar energy is trapped within, raising the temperature

Solar Concentrating Cookers Large mirrors or shiny surfaces are used to reflect and concentrate the

sun’s rays onto a small volume, thus raising the temperature

Combination Designs A combination of solar box and concentrating designs; concentrated

sunlight is fed into a solar box, further increasing the heating potential

Solar Home Design:

Site SelectionDirect GainIndirect GainControl Strategies

Solar Home Design: Site Selection

In the northern hemisphere, the south side of a building always receives the most sunlight.

For the best designs, solar homes should have large south-facing windows.

Solar Home Design: Direct Gain

Sunlight that enters the home directly and is absorbed and temporarily stored in the floors or wallsDaylightingThermal Mass

Let’s watch a video on Daylighting!

Let’s watch a video on Thermal Mass!

Solar Home Design: Indirect Gain

Solar heat that is blocked from entering the home directly, but then is transferred from where it is collected and stored to different areas of the house Trombe WallSunspaceSolar ChimneyThermosiphon

Solar Home Design: Control Strategies

Design elements that selectively block solar energy from entering or leaving the home.Overhangs (Roof/Window)Window GlazingBlindsInsulation

Let’s watch a videoon Cool roofs!

What’s Coming Up?

Active Solar Energy

Power Transmission

Impacts on Environment/Society