As we are approaching the beginning of the 2015, our mind goes to the EU’s targets to have all new building complying with “nearly zero energy” standards by 2020.
According to Jessica Grove-Smith, Benjamin Krick and Wolfgang Feist, of the Passive House Institute, Passivhaus standard may help to fulfil this requirement.
Strict targets have been set by the European Commission regarding the energy standard required for buildings: by the end of 2020 all new buildings in all EU member states required to comply with the ‘nearly-zero energy’ standards defined in the Directive 2010/31/EU. But what exactly does this mean and how can the Passive House standard help to fulfil this requirement?
The intention of the EU’s Directive is essentially to increase the energy efficiency level of buildings. The remaining very low energy demand of the so-called ‘nearly-zero energy’ buildings should then be covered to a large extent by energy from renewable sources, including energy produced on-site or nearby.
A single Directive; different implementations
The assessment of the energy performance and resulting requirement definition is to be evaluated “taking into account outdoor climatic and local conditions, as well as indoor climate requirements and cost-effectiveness” (article 1, paragraph 1). Member states are already working towards a quick implementation of the Directive by introducing market incentives and doing away with market barriers. National reports and plans of how the respective countries calculate the cost-optimal levels of minimum energy performance requirements, which will form the basis of the local nearly-zero energy efficiency targets, are being submitted to the European Commission. Unsurprisingly, the approaches taken on national levels vary, leading to higher or lower energy efficiency goals and legislations – mainly depending on the assumptions used for the cost-effectiveness assessment and on the parameters used as efficiency indicators.
Passivhaus – a single solution?
The long-established Passivhaus Standard provides a solution, which is in perfect agreement with the requirements set by the EU commission’s Directive. From the very beginning, in the 1990s, the Standard was defined as an energy efficiency performance level equivalent to the economic optimum over a building’s lifetime. This fact has since been confirmed in numerous studies for climates throughout Europe, even worldwide (see www.passipedia.org). As a definition for the ‘nearly-zero energy building standard, the Passivhaus Institute therefore puts forward the following proposal:
“A nearly zero-energy building is one that offers the best economic performance in terms of investment, energy, and capital costs under local climate conditions. The energy balance comprises overall energy demand for heat, hot water, and all electricity consumption along with renewable energy produced locally.”
In terms of numbers, this definition is met by the Passivhaus criteria (available on www.passiv.de) with a limited space heating demand (15 kWh/m2yr) or heating load (10 W/m2) and a maximum cooling demand (15 kWh/m2yr in Europe). It is extremely important to set such limiting values for the useful energy demand in addition to the overall primary energy of a building.
While the useful energy demand requirements for heating and cooling ensure long-term efficiency due to a good building envelope, limiting the overall primary energy is essential for an assess of a building’s total environmental impact. In addition to heating and cooling, the overall primary energy demand includes hot water, all household and auxiliary electricity, as well as losses from the performance of the energy systems and sources used.
PE as an efficiency and environmental benchmarking tool
The usefulness of primary energy (PE) factors as efficiency and environmental impact assessment are worth looking at in more detail. Conventionally these factors represent the (non-renewable) primary energy of a given energy source. This approach, however, has some serious problems as an efficiency and environmental benchmarking tool:
- The factors change with time in absolute terms and also relative to the energy targets
- They do not address severe environmental aspects such as nuclear waste or climate change
- They do not account for the limited availability of some energy sources (including renewables such as bioenergy)
- The need of energy storage is not taken into account
A new primary energy assessment method
Currently, the limiting (non-renewable) PE criterion for Passivhaus is 120 kWh/(m2yr). However, this value is about to change with the formal introduction of the next Passivhaus Planning Package (PHPP). The existing PE benchmark will be replaced with a new renewable primary energy assessment method (PER). Based on the local availability of solar PV and wind resources, this approach models a reference scenario of a future energy network entirely supplied by renewables, including energy storage and accompanying losses. The overall required renewable primary energy of the building at hand is then calculated with separate PER factors for each energy consumer.
Passivhaus buildings that reach the useful energy demand criteria will then be grouped into three different classes – classic, gold, and premium – depending on the PER demand and on-site renewable energy production.
In line with the EU Directive for nearly zero energy buildings Passivhaus is thus providing cost-effective energy efficiency and on-site renewable energy production optimised for the local conditions.
Photos: Holy Trinity Primary School - Architype/ Leigh Simpson Photographer & (Cover) Passive House Bruck - Peter Ruge Architekten /Jan Siefke Photographer
Article originally published on Building4Change