Before my interest in using the sun my Wife and I purchased a HUD home to fix up and make our own. Little did we know the power of using the sun to lower our utility bills. One of the first things we noticed while rebuilding this house was the orientation of it seemed great for the hot desert summers in Las Vegas. Our last house faced West, which meant our living room in the front of the house was like an oven. We replanted the grass in the front yard 3 times before we finally gave up and moved to desert landscaping. Another problem associated with facing west is my garage was also an oven (and I love my garage). Our current house faces north. The first benefit I noticed is even in the summer time the sun does not directly shine into my garage (much joy). We purchased the house in September and got our first taste of solar heating that winter. Now most people think, you live in the desert...it isn't that cold. Well nothing could be further from the truth. Our elevation is over 2000 feet which makes it quite cold in the winter. Along the back side of our home (facing south) we have a large amount of windows that rise up to our 19 foot ceilings in our dining room, and living room. We laid ceramic tile throughout the entire first floor, and soon noticed that if we left the blinds and curtains open during the day, that the tile would heat up and warm the rest of the house. In the winter when it is in the 40's outside it is a nice and toasty 75 to 80 degrees in our home.
Now that you know the history let's move on to the solar room. I started reading all I could about the concept of solar power, and decided we could benefit from a solar room on the back of our house. The main reason for this is that solar rooms are only effective when they can face south (for more information visit our Passive Solar Heating page). We had already built a pergola onto the back of the house to shade our living room in the summer. This will be the basis of our new solar room. One of the problems we currently have is since we live in a 2-story house with 19 foot ceilings in the living room and dining room. When the sun sets the heat generated in the day rises and keeps our upstairs warm, and our family room is very cold. The solar room will add extra protection from the cold outside and help out our heater to warm that area.
Solar Room Basics
There are some very key features when creating a solar room for it to properly work. The basic concept is simple, you have a very well insulated room that has a large amount of south facing glass in order to take advantage of the low winter sun. The sun passes through the glass and heats the floor that is made of some sort of masonry, that will hold that heat for the evening time. The heat that has built up during the day will naturally heat our living room by convection. This happens naturally because heat always moves to cold. The room must be very well insulated in order for the cold outside not to cool the area at night.
Our Solar Room
Our living room has a large window on the right and a standard 6 foot slider on the left, leading to our backyard. Now even though glass is needed to allow the sun to shine in and warm your home it is also the most non insulating piece of your home. The patio slab that is just outside is 16 ft. wide and 10 feet deep. This is going to be the foundation for our solar room. Along with heating our living room it will also expand our living area by 192 square feet.
Our solar room will have a double pane non-low E 8 foot slider centered on the front wall of the solar room. On either side of the slider will be 36" W x 48" H non-low E windows that are also double pane. The reason for using non-low E glass that is double paned is you want the solar radiation to enter the room (non-low E), and you want to keep the heat in (double pane). The side walls (facing east and west), will have 2 small Low E double pane windows placed up high and close to the house. These windows will be about the size of the windows you see above showers about 24" W x 12" H. The use of the windows will be to create a cross breeze to cool the room in the summer. These windows are placed high because heat rises, and using the cross breeze will help reduce the build up of heat. Another key feature that will help to evacuate heat in the summer is by using a solar powered attic fan. This will be placed towards the highest point of the ceiling to make its job easier.
The choice for flooring will be a dark colored slate. Everyone knows that darker colors absorb more heat, and since the flooring is a masonry product it will act as our heat storage. Along with using the sun to heat this room in the winter we are also going to experiment with radiant floor heating. The current patio slab is about 3 inches lower than the bottom of our slider. This will give us plenty of room to lay the PEX tubing in a serpentine fashion and pour concrete over it. Another part of this flooring will be Foil/Foam Insulation and 6 mil plastic. The foil insulation will be used to insulate the flooring from the cold earth, and the plastic will create a moisture barrier, so that ground moisture does not come up through the slab. The water in the radiant floor system will be heated using the sun. We will create a solar collector to heat the water and use a small pump to pump the water through the PEX tubing. The best part of using radiant floor heating is since heat rises, the best place for that heat to start is from the floor.
During the winter the axis of the sun's rotation is lower than during the summer, so to help keep the hot summer sun from overheating the solar room we will also incorporate an overhang over the south wall. A general rule of thumb is that your overhang should extend half of the height of your south facing glass. This way the low winter sun will shine in and the higher summer sun will be shaded. Now this is a "rule of thumb", for the actual length of the overhang you should find out the exact angles of the sun's axis relative to your latitude. A person living in Canada will require a different overhang length than we will living in Southern Nevada (there are a number of resources for finding this information online, or you can hire a Solar Consultant).
This is the plan. Be sure to check back to see photos of the construction of our solar room. We will also inform you of any pitfalls we experience along the way.