Questions related to the EPB standards on the building as such (M2)

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Energy needs for heating and cooling and indoor temperatures:

Why does EN ISO 52016-1 contain a monthly calculation method in parallel with an hourly method?

Several countries have many years of good experience with a simple monthly calculation method.

However, a calculation method using hourly time intervals is much better suited to deal with low energy buildings and innovative (dynamic) technologies, while also being better at evaluating indoor environmental quality which is an important aspect in the revised EPBD:2018.

To facilitate and stimulate the change over from monthly to hourly calculations, the new hourly method in EN ISO 52016-1 has been tailored in such a way that it does not require more input data from the user than the monthly method.

Also for the calculation of technical systems with their dependence on operational and climate parameters, an hourly method becomes simpler than a monthly method. A monthly method requires e.g. pre-calculated correction factors, to be derived from hourly considerations, which would have to be defined on a national basis depending on climate and technologies.

Read more at the page on EN ISO 52016-1 which includes also links to recent papers with further explanation on the subject.

2019-07-22

How does the hourly calculation method in EN ISO 52016-1 (to calculate indoor temperatures and heating and cooling loads and needs) relate to dynamic building simulation tools?

The hourly calculation method can be considered as a simplified dynamic simulation. It is designed to reduce the need for input data to the same level as the monthly calculation method, while keeping the dynamic representation of a zone with its building elements.

Dynamic building simulation tools have more detailed methods in several places, which may differ between the tools. For compliance testing usage it is advantageous to have a prescribed method in place. However, additional standardization work is in preparation (ISO/TC 163/SC 2/WG 15 & CEN/TC 89) to make the hourly calculation method according to EN ISO 52016-1 more flexible without jeopardizing reproducibility and transparency.

In EN ISO 52016-1, clause 7.2 includes already a selection of verification cases, which stems from the ASHRAE 140 Standard, which is dedicated to the validation of simulation tools.

Read more at the page on EN ISO 52016-1 which includes also links to recent papers with further explanation on the subject.

201-07-22

Why is a calculation method using BINs not an option?

The "bin method" refers to a procedure where monthly weather data are sorted into discrete groups of weather conditions (bins). Each bin contains the number of hours of occurrence of a particular range of weather condition, during an average month or year. For instance the outdoor air temperature.

The energy performance of a specific element of the building or system is calculated for each bin and the weighted sum for all bins is an estimate of the performance over the total period. See more explanation in the link below.

The bin method is kept only as a tool in (other) EPB standards to calculate specific generation devices like heat pumps and cogeneration units in the context of a monthly calculation method.

An hourly method (already included in the set of EPB standards) is much more flexible to calculate heating or cooling needs and to describe the interaction with and between the various technical systems, for instance because each system has a different time schedule.

Another important limitation of the bin method is that there is no 'memory' between the bins. In case of energy storage systems or in case of heat accumulation in building elements, a bin does not know how much heat was accumulated or released during the previous time interval, because the bins are not sequential in time in contrast with the calculation using a sequence of (e.g. hourly) time intervals.

This limitation is the reason why a bin method is not an option for the calculation of the energy needs for heating and cooling in a building: the heat accumulation in the building mass typically stretches over several days.

Errata in the EPB standards:

Where can I ask questions or submit comments if something is unclear or maybe wrong in one of the EPB standards under this topic?

Please contact us if you have a question or comment on one of the EPB standards…

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