What if we looked at that slightly differently and said that a “sun” was the measure of one day. 10,000 suns/365 days in a year = 27.4years. That’s almost the same time frame that the Meteonorm software, referenced in the PHPP manual, uses for one dataset of its climatological periods. When thinking about your project’s climate data, now you can think in terms of the heat of 10,000 suns (days) averaged over an Annual or monthly period for a specific location.
What we are looking at this week is not how the climate data was gathered, but rather how it is applied in the PHPP. There are two methods to choose from for the Annual Heat Demand. The Annual method is used for projects that have heating demands that exceed 8 kWh/(m2a) AND free heat/heat losses > 0.7. According to the PHPP, if your project does not fit that metric, then you should use the Monthly method that is more precise in determining the effects of both orientation and shading on your project. You choose which method you will use on the Verification worksheet, but since we are discussing how to fill in the Annual Heat Demand and Monthly Heat Demand worksheets I wanted to go over that again.
The Annual Method Worksheet gets most of its information from a variety of other worksheets such as the Areas, Windows, Ventilation, and Verification. There isn’t much that you need do on this worksheet. As a matter of fact, the only cell you can change is the room height and the PHPP cautions you not to exceed 2.5m or you will have an issue with the air change rates on your project being over dimensioned.
The Monthly Method Worksheet gets all of its information from other worksheets – there isn’t anything you can change on this worksheet. What it does provide is the graph that shows the heat balancing for all the months of the year. By taking the heat gains and comparing them to the heat losses you can see graphically how much additional heat will be needed for different times of the year as well as how much excess heat is generated that will require additional shading strategies.
These worksheets give you a snapshot of your project’s heating conditions and allow you to analyze your project to see just where the heat losses and heat gains are occurring and at what level. If you are having a problem meeting the requirements, this can help direct you to where you might find a solution in the form of more shading, smaller or larger windows, more insulation, etc.
So harness the heat of 10,000 suns! Use the PHPP to plan out your project and take advantage of the intricate physics that went into figuring out just how to determine the projected heating and cooling conditions of your project before it is ever built.
Next Up – Heating Load