Balance Point Temperature - tough maths made easy

Identifying the balance temperature of your building is the first step to classical energy management.

This post does three things:
  • It looks at a far easier way to get the job done
  • Explains why it is so important,
  • Details how some newer diagnostic technologies can really enhance the understanding of heating and cooling in buildings
here we go...

So, a far easier way to get the job done

Here is a very quick video showing kWIQly automating the mathematics for a client building. All kWIQly needs is a history of energy consumption associated with heating or cooling, and to know where your building is.

Given Latitude and Longitude or an address kWIQly grabs the weather data - saving you the trouble.

There is a thorough description of the process done the "hard way" at Berkley Uni.

but then ... Why would you ?

Why is it so important - the easiest way to understand the concept is by interpreting the graphics.

Here is a fixed-screen shot for reference: 

The balance temperature or balance point temperature is (for heating) the outside temperature when you are just on the border of needing heating or not. (11.5 Celsius above).  Above this is summer base load - and below weather response (or did you watch the video !)

Different buildings are different sizes, have different insulation, glazed areas, typical weather exposure, shade and etc, plus they have different accidental ( organic heat gains ), coming from Pcs, lights , people, cooking and so on.

But this single temperature takes all of that into account. 

On one side of it all heating effort is waste (or contributes to greater cooling costs!) including pumps to circulate heat, boilers on low load and so on.  

On the other side bare minimum heat should be available (as cold as compensation of zones allows) and for a absolute minimum period of the day.  Why the bare minimum ? - because plant is often very inefficient on very low load.

That will be enough to heat the "chillier corners" of the building.  As temperatures fall, a liner response pattern develops, and it should remain linear all the way to the coldest outside temperatures that the building experiences.

Newer diagnostic technologies

Update February 2012 : You can now get degree-days for anywhere on the planet calculated for free by kWIQly

In reality, the balance point temperature is not fixed.  It is dynamic for three reasons:

  1. It moves lower if a building is unoccupied and internal temperatures are allowed to fall (because heat loss is slower),
  2. it falls if the ventilation rate falls, and curtains are drawn(no need to heat all that cold outside air before you put it into the building and better insulation),
  3. but it rises as internal activities fall.

So depending on the nature of the building and its occupancy patterns, the temperature at which you should make sure no heating can happens moves - getting it wrong is wasteful - always !.  

Control systems can easily be set up to maximise the benefits from this phenomenon, but first you need to do the maths!

Happily with smart meter data available, we can automate all of that, so 
a) send us your data, or better
 b) have a word with your smart-metering company or utility and have them get it to us.

 The rest is a piece of