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--- certification:passive_house_categories:per [2024/04/18 19:08] – jgrovesmith
+++ certification:passive_house_categories:per [2024/04/18 19:11] (current) – jgrovesmith
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 ===== Introduction =====
-The so-called PER concept (Primary Energy Renewable) were first introduced by Wolfgang Feist at the 18th International Passive House Conference, as future-oriented sustainability assessment criteria ([[basics:passive_house_-_assuring_a_sustainable_energy_supply:passive_house_the_next_decade|Passive House – the next decade]] [Feist 2014]). With the release of the Passive House Planning Package (PHPP) version 9, PER was then introduced as a worldwide certification criteria for [[certification:passive_house_categories|Passive Houses Classes]].
+The so-called PER concept (Primary Energy Renewable) were first introduced by Wolfgang Feist at the 18th International Passive House Conference, as future-oriented sustainability assessment criteria ([Feist 2014] [[basics:passive_house_-_assuring_a_sustainable_energy_supply:passive_house_the_next_decade|Passive House – the next decade]]). With the release of the Passive House Planning Package (PHPP) version 9, PER was then introduced as a worldwide certification criteria for [[certification:passive_house_categories|Passive Houses Classes]].
 This article describes the general methodology used to derive the PER-factors for electricity.
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 ===== PER factors for electricity: The methodology =====
-The methodology used to derive PER factors is based on the ideas that have previously been published in [Feist 2013] and [Feist 2014]. The approach described in these original publications were further developed, applied and analysed internationally, as outlined in this article. With an hourly resolution load profiles of the energy demand are simulated in the context of a future scenario - where the energy is supplied solely from renewable energy sources, including all necessary storage facilities (Figure 1). The individual calculations are based on climate data from various sources, the resulting PER factors describe how much more renewable energy must be supplied in order to cover the final energy consumed at the building, including all losses incurred along the way. For example, a PER-factor of 1.5 indicates that a surplus of 50% renewable primary energy has to be generated in order to be able to meet the final energy demand at the building.
+The methodology used to derive PER factors is based on the ideas that have previously been published in [Feist 2013] and [Feist 2014] (see [[basics:passive_house_-_assuring_a_sustainable_energy_supply:passive_house_the_next_decade|Passive House – the next decade]]). The approach described in these original publications were then further developed, applied and analysed internationally. With an hourly resolution load profiles of the energy demand are simulated in the context of a future scenario - where the energy is supplied solely from renewable energy sources, including all necessary storage facilities (Figure 1). The individual calculations are based on climate data from various sources, the resulting PER factors describe how much more renewable energy must be supplied in order to cover the final energy consumed at the building, including all losses incurred along the way. For example, a PER-factor of 1.5 indicates that a surplus of 50% renewable primary energy has to be generated in order to be able to meet the final energy demand at the building.
-{{:picopen:per_formel_en.jpg?400|}}
+PER-factor  =  Δ(Energy supply from renewable sources) / Δ(Final energy demand at the building)
 The PER factor is determined by the simultaneity of available energy resources and the energy demand, as this dictates how much energy needs to be temporarily stored before it is used. Short-term storage can technically be achieved fairly efficiently, whilst longer term seasonal storage will always cause higher energy losses. Depending on the load profile, the energy demand will partially be covered (a) directly from the renewable supply, (b) with energy that has temporarily been buffered, or (c) with energy from a seasonal storage. As a logical consequence of the temporal correlations, heating – which occurs only during seasons with low RE availability – is highly energy intensive in the envisioned future supply chain. For cooling, on the other hand, a larger proportion of the associated energy demand can be used directly without need for temporary storage and losses. Load profiles that occur throughout the year (e.g. domestic electricity use, hot water) lie within these two extreme scenarios.