Using balance point in new and retrofit building calculations
user-723121
| Posted in Energy Efficiency and Durability on
Does anyone take into consideration balance point temperature when designing new homes or in planning energy retrofits for existing residences. A lot to contemplate.
https://en.wikipedia.org/wiki/Balance_point_temperature
Energy modeling programs tie it all together but it is sometimes difficult to isolate various factors.
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Manual-J load tools typically report a calculated balance point, but it's not particularly relevant to most of the design. It's a very squishy number, since occupant behavior, solar gains etc can affect the day to day balance point by quite a bit. A sunny day in January with a lot of snow-reflected gain can drop the balance point by 10F or more during the daylight hours, a gang of kids having video game session with multiple gaming machines running can too.
The relevance of balance point is primarily to the setup & operation of the heating/cooling systems.
Thank you, Dana
The world is rife with squishy numbers, I was hoping for more from balance point temperature. Solar gain and thermal mass storage is one area that interests me with regard to balance point temperature. Today in Minneapolis the sun is shining at 11:30 AM, the furnace has not run for the last hour and the outdoor temperature is 35F. I guess this is my balance point currently, it will be much different after the sun sets today.
>"Today in Minneapolis the sun is shining at 11:30 AM, the furnace has not run for the last hour and the outdoor temperature is 35F."
Having a heat wave? :-)
Keep in mind that Manual J is (roughly) about peak loads. At 5AM, there will be fewer internal sources of heat.