There are plenty of energy calculation software that claims accuracy, but there are no national method to substantiate these claims. The result is a wide array of software from complex simulation models like VIP+ to simple excel sheets and everyone (incl VIP) says that there software is calculating correctly. This leads to a general suspicion against calculation software. This is clear when you look at ByggherreForums remiss answer regarding energy declaration and CEN-standards. Where CEN is saying more or less that there is little accuracy in energy calculations.
Our experience is exactly the opposite, you can with high precision calculate how much energy a building should consume.
On a national and international level there is attempts to incorporate standards and methods that are not tested, quality assured and verified in any basic method what so ever.
It is time for a national certification method
To develop a energy simulation system with acceptable accuracy takes about 50-80 man years. To develop a simple system that calculates after a degree day curve takes about 2-3 days. There should of course be no way to compare these systems, but that is precisely what is dome today. Simple excel spreadsheets claim +-10% accuracy. Lack of test method also gives other symptoms. Effektiv is financing review of program according to user interface!!! STEM is financing development of useless tools!! Distributors , academics and consultants can use any tool they want. CEN standards can be proposed without any quality assurance and testing at all. In the swedish law proposal regarding energy declaration they want to use statistics as base for energy performance!!! Government can require that not verified methods shall be used etc etc.
A proposed method requires 4 steps.
Step 1 is ready and is available free on internet.
Step2-4 probably requires and should be done in accordance to Energy declaration project.
1 IEA-Bestest
Gives a good picture of how the program can handle fundamental building physics.
The Ashrae-bestest can also be used.
2 Infiltration-Bestest
Develop a Infiltration Bestest (if there is not any ready) that shows how the program can handle air leakage and internal thermal. This is crucial to evaluate how well the program can handle energy simulation and investment calculation.
3 Installation-Bestest
Develop a Installation Bestest (if there is not any ready) that shows how the program can handle hvac equipment.
It should handle.
- Ventilation, multiple units with heat exchange
- Heat
- Cooling
- Different types of heat pumps
- Solar panels
- Sewer heat exchange
- Multiple operational schedules
- Economical and environmental calculations.
HVAC-BESTEST is to limited to be used but it gives a very good structure to work from.
4 Validation against real object and real years
A group of well documented buildings of different kinds. This gives in the end a answer how well to program handle all aspects integrated and practical.
This method gives a good feeling for what the program can handle and where it can be used. Any proposed method can be verified with limited work.
We will finally have an end to disputes about what method to use templates, statistics or simulations as base for energy performance. Let any developer use this methods himself, it should only take a couple of days and we can then easily see how reliable their system is.
