Passive Solar Heating Part 2

November 1, 2011


We talked last month about using a skylight for direct gain during November, December and January but then shading the skylight during the other months preventing most of the heat gain. We still want daylighting. We want the shading device to be over the outside of the skylight and to be automatic not needing physical adjustment.

One possible solution is a set of horizontal metal fins placed east/west over the skylight and supported by light weight metal frame. The fins would allow full direct sun penetration in December, partial penetration in November and January, and no direct penetration the rest of the year. The metal would be aluminum for light weight and strength. The finished product would be rigid and able to withstand the strong winds here. Indirect light would reach the skylight by bouncing through the louvers and by daytime diffuse sky radiation. 

Are there other solutions? I believe so.  Let’s see if my readers can come with other solutions.

Now we want to provide cooling, especially during April, may, June, July and August. We can do this by reducing heat gain and by providing good air movement. We want to make sure that all heat sources are reduced or eliminated.

First make sure all glazing is in shade for the entire day. Second, eliminate internal heat and humidity as much as possible. We will place the a laundry room next to the kitchen with the clothes washer, clothes dryer and hot water heater located here. We will vent the laundry room and close off the house. In the winter we will open the house to the laundry and close it off to the outside. We can do this with a door to the house and a door to the outside. If we place the refrigerator and stove on the wall connecting to the laundry room, we can vent these appliances into the laundry.

We begin by providing natural ventilation from south to north through the house. The south vents should be less than the north vents. The air movement should be directed over where people sit. We then provide ventilation from the north to the south during the nighttime.

For the bathrooms, we want to provide both natural lighting and venting. This can be done with a special flat solid top skylight and frosted glass sides that are also vents. The vents may be closed in winter if needed.

We can provide high up roof vents for induced ventilation. This venting works without fans. Then we provide overhead fans for places we sit, and for the bedrooms. We also provide fans for outside porches. This provides cooling and protection from the mosquitoes.

One unusual idea we could use are radiant floors for both heating and cooling. The major expense for this system is the concrete and tile floor which we already have. We just need to add the piping and a pump. In the summer, we switch over the water to incoming domestic water supply. The pressure of the system will run the water through the floor pipes on the way to a faucet. In winter for heating, we can run the hot water from a solar collector or water tank through the pipes when you take a shower. Since this hasn’t been done before, is there anyone willing to give it a try?

These are not the only ways to cool a home. Rather these are the basic approaches and some options. If you have others you would like to discuss, please contact me at

The Lake Chapala Green Group meets the first Tuesday of each month, 3:00, at the Lake Chapala Society, Neill James Patio. The general meeting is suspended for the months of June, July and August. For information on all things green at Lakeside…