The Progress of Passive House - 88
From Classic to Plus & Premium certified classes
The energy supply market is rapidly shifting from fossil fuel to renewable sources. This transition is necessary, not only to comply with European targets and international and regional protocols on climate change (20% share from renewables on total energy supply by 2020), but it’s also the most responsible way to promote energy security. The European Directive on the Energy Performance of Buildings, which constitutes the main reference in setting the targets for the entire sector, established that by the 31st December 2020 all new buildings must be nearly zero energy buildings (NZEB). The Directive also specifies that “The nearly zero or very low amount of energy required should be covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced on-site or nearby”. It also aims to “encourage architects and planners to properly consider the optimal combination of improvements in energy efficiency”.
The Passive House concept is constantly evolving. Passive House technology, design and techniques are thought to adapt to new environmental and building challenges. In a scenario where NZEB requirements set the target to aim for, while encouraging a full transition to renewable energy, the Passive House Standard represents a major facilitator in this changeover. The International Passive House Association notes that renewable energy is the ideal complement to the efficiency of the Passive House Standard (see Passive House & Nearly Zero Energy Buildings), and offers a guidance for this combination. In 2015 in fact, bringing the Standard much closer to the nearly zero energy requirement, two new classes for the qualification of Passive House buildings have been introduced: Passive House Plus and Passive House Premium (in addition to the existing Passive House Classic).
Passive House Classes: Classic, Plus, Premium
Passive House Plus and Premium feature the same characteristics of the Classic model, with additional renewable resources on site or nearby, further increasing the efficiency of the energy performance. This new categorisation is based on buildings’ energy demand and power generation. While energy demand for annual heating remains fixed at a maximum of 15 kWh/m²a, the demand for primary energy for PH Plus and Premium differs in terms of values and evaluation. If before the non-renewable primary energy factor was considered, it is now replaced by the renewable primary energy factor (PER – Primary Energy Renewable). PER factors that are determined for the individual energy applications state how many kWh of renewable primary energy must be generated for one kWh of required energy at the building. Also different from the usual evaluation method, renewable energy production is estimated with reference to the projected footprint of the building (technically defined as the vertical projection of the thermal envelope towards ground), instead of being related to the building’s floor area. In order to address regional and seasonal issues with availability of renewables, a short-term and a long-term storage systems are available. These adjustments to the upgraded versions (Primary Energy Renewable and calculation criteria) are assimilated into the latest edition of the Passive House design tool: PHPP 9.
Overall, the parameters featuring different type of buildings can be summarised as follows (see The new proposed passive house classes explained):
Energy Saving Building: Space heating demand max. 30 kWh/m2yr; PER demand max. approx. 75 kWh/m2tfa*yr.
Passive house Classic: Space heating demand max. 15 kWh/m2yr; PER demand max. 60 kWh/m2tfa*yr.
Passive House Plus: Space heating demand max. 15 kWh/m2yr; PER demand max. 45 kWh/m2tfa*yr; Primary electricity generation min. 60 kWh/m2ground*yr based on the building’s footprint.
Passive House Premium: Space heating demand max. 15 kWh/m2yr; PER demand max. 30 kWh/m2tfa*yr; Primary electricity generation min. approx. 120 kWh/m2ground*yr based on the building’s footprint.
CategorySpace heating demand*PER demand *Primary electricity generation**Energy saving building30 kWh/m2yr75 kWh/m2tfa*yr.—Passive House Classic15 kWh/m2yr60 kWh/m2tfa*yr.—Passive House Plus15 kWh/m2yr45 kWh/m2tfa*yr.60 kWh/m2ground*yrPassive House Premium15 kWh/m2yr30 kWh/m2tfa*yr.120 kWh/m2ground*yr
*Max. ** Min.
While the Passive House Classic still exhibits a great achievement in terms of energy efficiency, PH Plus and Premium represent the natural evolution of the Standard towards zero energy buildings, and play an active role in the energy and policy shift from fossil fuel resources to a zero-carbon alternative.
