The ABC's of the PHPP - Part 15 IHG - Fitting Square Pegs into Round Holes

Anyone who has had to customize anything knows the feeling of trying to fit a square peg into a round hole.  For some circumstances the process is easier than others – you can always cut a piece of wood shorter, but cutting a piece of wood longer?… that’s a trick.  Fortunately the PHPP understands that there may be times when your Internal Heat Gains are going to vary from the standard entries and it has a way for you to fit that square peg into that round hole or cut that piece of wood longer.

First, how do you determine what the standard use calculations are compared to what it is that your project is going to use?  Look at the PHPP manual under section 26.3 “Explanations for Energy Services”.  This will tell you what is considered the standard values.  If you know you are using something that does not fit these definitions, then you will need to use the IHG worksheet to alter how the PHPP looks at your Internal Heat Gains (but be prepared to justify it to PHI when you have your project certified).

If you look at the IHG worksheet you will see that it is almost entirely filled in by the Electricity and Aux Electricity worksheets.  There really are only 2 cells that you can enter anything into… but there are several circumstances that affect how this worksheet changes the PHPP. 

On the Verification worksheet you will have declared what kind of building your project is – you see that choice reflected on the IHG worksheet in the “Utilization Pattern” and “Type of Values Used” selections (Cells B4 and B5) .  If you selected a standard residential building you can expect the PHPP to use one set of calculations for Internal Heat Gains, a standard school or retirement home will use a different set of calculations.  But what if your home is not going to use electricity in a standard manner?  That is where you can change the way the PHPP sees the Internal Heat Gains. 

If you look at the IHG worksheet, cell 05, you see a comment to the left of the cell depending on what you have set your Verification building use as.  If you selected Standard Residential you will see the comment “No Entry Required” and, as it says – no entry is required.  If instead you chose to describe your building as “Residential” and “PHPP Calculation Residential Building” you will see the comment “Enter Result from Above Line Here”.  (This is because a circular logic error would have occurred had the PHPP been programmed to enter the number in that cell automatically and it needs you to do it for it.  If you make an error entering in the number it will show a “False Entry” error.)

When you selected “Residential”, “PHPP Calculation Residential Building” you will also notice that some other comments pop up on the IHG worksheet header area.  One says “Calculation from this Worksheet” (it will say that the calculation is from the IHG Non-Dom worksheet if you told the Verification worksheet this was a non-residential project) and another says “Carefully complete the Electricity worksheet!”  The caution to carefully complete the electricity worksheet is so that you accurately reflect the usage and therefor the internal heat gains that are to be expected on this project.  You will need to justify this usage to PHI during the verification of your project in order to officially use these numbers.

If you chose a “Home for Elderly or Students” you will have the same options as “Residential” depending on if you were using the standard usages or “PHPP Calculation Residential Building”.  You will notice that instead of the comment next to cell O5 saying “Enter result from Above Line Here” it now says “Manual Entry”.  You will still enter the amount from the above line.

There is one final entry possibility for the IHG worksheet.  You may have said the “Utilization Pattern” is “Other”.  When selecting this choice of Utilization Pattern you will still be presented with the “Manual Entry” comment that will require you to enter the amount from the line above if you choose “PHPP Calculation Residential Building” but if you chose “Manual Entry” for the type of values used you will notice that cell O4 no longer has a number in it and you are allowed to manually enter any value into cell O5.  You must be able to justify this choice and I recommend consulting with PHI early on in the design of your project to make sure you are approaching your electrical calculations correctly.

The final cell on this worksheet that can be altered is cell S30.  This value will be the amount of heat that is available from the “Other” electricity sources you entered on the Electricity worksheet in cells H28-H30.  You will notice that Lighting in this section of the worksheet is rated at 1.00 availability while dishwashing is listed as .30 availability to be used for Internal Heat Gains.  The PHPP manual explains that the heat in the dishwater that is sent down the drain is no longer available for Internal Heat Gains once it has gone down the drain, but the heat from the lighting stays within the building.  You will need to look at what “other” electrical sources you have listed and determine what the availability of the waste heat will be to your building and enter the appropriate amount in cell S30 (1.00 = 100%, .5 = 50%, etc.)

And that’s all there is to the “How to fit a Square Peg in a Round Hole” guide to customizing the Internal Heat Gains in the PHPP.

Next Up – the Compact Worksheet.