Passive Solar Design
Humboldt County’s latitude is aprox 40.7 degrees North.
The longitude is 129.9 Degrees West.
http://www.physicalgeography.net/fundamentals/6h.html
Solar Angles Calculator
http://www.srrb.noaa.gov/highlights/sunrise/azel.html
A brief of what passive solar design is.
Humboldt County, passive solar building design has been proven to work and create a beautiful, enjoyabe and cost saving way of living on the North Coast. If you live in a passive solar home or know someone that does The Humboldt County Green Building Program and public want to hear from you.
What is passive solar? Passive solar building is the design of buildings where the walls, floors, roof, and windows collect the sun’s thermal energy (heat) in the winter. In the summer the functions of the building are reversed to where the sun’s thermal energy is then blocked. The word passive is used because these two functions of the building are done with out the use of mechanical or electrically driven motors, blowers, or heaters.
When building a new structure on a piece a property, lot, city block and especially when developing an entire sub-division it is extremely important to orient the building properly with respect to the sun’s relationship to the site. By using a compass or smart phone (on location) find true south. The goal is to orient the structure(s) so to utilize the sun’s radiation from the east south and west during as much of the year as possible. This is best done by designing and orienting the structure as somewhat of a rectangle with the long sides running East to West. Natural features will play a major role in this phase of the design processes.
On the coastal region of Humboldt County one might not want to have any trees on the south side of their home as to allow as much insolation (the sun’s radiation) into the structure as possible. The reason is structures have specific heat capacities, meaning an ability to hold onto the direct heat radiation coming in. When the structure(s) is not being shaded, this decreases the need for back up heating, like fireplaces, electric heaters or gas heaters.
If the structure is located in a warmer region of the county or in Trinity County, the application of deciduous trees being planted along the South and West sides of the building can function with great value. Deciduous trees loose their leaves in the winter, allowing sun (warmth) in, they regenerate new leaves in the summer months creating shade over the hottest portions of the structure(s). Exterior blinds over the east and south windows block the heat during the morning, helping store more of the coolth from the night before.
Some tips for designing passive solar homes.
Understand your location over the entire solstice year. During the winter months here in Humboldt County the sun is at a lower degree of an angle from the horizon and in the summer the sun is higher up in the sky (larger angle of degree). To understand the correct terminology and to calculate solar angles for your location please visit the links on the side.
We now know that we want heat to enter the home in the cold seasons. But how much heat do we want, how will it enter, how will it last and how will it not escape or how will it escape? Those are the questions you need to answer during your design process.
More key items when designing a passive solar building.
Climate
Window Placement and glazing type (please review our section on windows).
Glazing to wall ratios.
Thermal Mass ratios
Compass orientation of the building
Specific Heat Capacities of building materials
The R-value and U-values of building envelopes.
Tip:
Insulate and construct a tight building envelope.
Tip:
Air changes can move warm air out and bring cold air in. It is very important to have a tight built envelope to a building. One can always open a window or door if the condition of the space gets unbearable.
Tip:
Do not use to many windows. This is called over glazing, in the 1970s during a rush in the construction of passive solar homes; many of the houses built were over glazed. Over glazing can overheat the building creating a very uncomfortable residence. Proper glazing to wall ratios is a very important piece to design a well functioning passive solar house and should be read up on in great detail.
Tip:
In competition with building and sustaining a tightly constructed building envelope, the building must also provide fresh air while not destroying the thermal characteristics and functions. Some say that two thirds of the entire air volume in a home should be recharged every hour. Installing controllable exterior-wall fans in the bathroom(s) and in the kitchen zones should be able to accomplish this, do not rely on the accidental air leakage of the building.
Tip:
Passive Solar Houses can come in a wide range of designs and have been a staple in buildings for thousands of years.
An Example of glazing and thermal mass working together.
In January (as the sun is lower in the sky) a South-facing window allows thermal energy from the sun’s radiation to enter the home, the radiation then heats up the slate floor “filling up” the slates thermal capacitance with warmth. The sun then goes down and night emerges with colder temperatures. The slate’s process then reverses and releases the heat to the cooler surrounding air. This process can work in the opposite way in the summer months. To learn more about this please read The Passive House Book by Kachadorian or The Solar House Book by Chiras. When thermal mass is applied correctly in construction design it can save tens of hundreds of thousands of dollars in heating a cooling costs over the lifetime of the building.
There have been many trial and error passive solar homes and building practices. The Humboldt Green Building Program has just given you the bare introduction to this form of construction. Please learn more about passive solar design by surfing the web and by reading either The Passive Solar House book or The Solar House Book. “I have read them both in their entirety and highly recommend them.” Ty Kearns, Humboldt Plan It Green, degree in Energy Management from Sonoma State.