Passive houses: EnerPHit certificate and Passivhaus certificate
superadmin
December 20, 2016
You have surely heard of the concept “passive houses”. Below, we explain what it is and what criteria must be met to obtain the Passivhaus certificate, for new construction work, and the EnerPHit certificate, for rehabilitation works.
What are passive houses?
As the Passivhaus standard guide from Fenercom (Foundation for Energy of the Community of Madrid) reminds us, the concept of “passive house” begins to be used in the energy context of the construction sector, offering a completely new and unprecedented vision in our country. Passivhaus does not aim to implement different types of renewable energies in inefficient existing constructions in order to approach energy self-sufficiency. What it proposes is to carry out constructions that consume the “minimum energy necessary”. To achieve this, it offers a method of action, that is, a series of steps that affect both the design process and the execution process, enabling the achievement of buildings whose energy demand for thermal comfort is minimal.Knowing that all professionals from all disciplines must work together to achieve the best results, the Passive House Building Platform (PEP), besides carrying out intense dissemination work in all corners of our geography with the help of its partners and the contribution of regional energy agencies, seeks synergies with other sustainable building certifications.
EnerPHit: Passivhaus standard (passive houses) for rehabilitations
With less strict conditions than the Passivhaus certificate, specific for new construction works, the institute also offers the EnerPHit certificate, specific only for rehabilitation works.The useful life of a building is very long. Therefore, all actions we undertake for its improvement and good aging must be cost-effective over time. Thanks to advances in knowledge and technology, it is now possible to take energy efficiency to the extreme, improving the envelope of our buildings and making the most of both external and internal thermal gains. Not using these resources we have at our disposal condemns buildings to new rehabilitation actions, besides wasting the opportunity to guarantee them a long life in optimal conditions of habitability, functionality, and aesthetics.
Experience has shown us that it is possible to carry out an energy rehabilitation of buildings using Passivhaus components, so that all the benefits of its application can be achieved, such as improving indoor air quality, enhancing thermal and acoustic comfort, drastically reducing energy consumption and, as a consequence of all the previous points, a revaluation of the buildings.
Regarding the limitation of energy demand and the airtightness of the building, the Passivhaus standard stipulates very demanding requirements. Due to the difficulties involved in rehabilitating an existing building, in these cases the certificate offered is EnerPHit, specific for rehabilitation works. More flexible than the Passivhaus certificate, it maintains its principles and applies specific solutions that adapt to the particularities of the buildings to be rehabilitated.
What are the differences between the EnerPHit certificate and the Passivhaus certificate?
According to the Passivhaus certification, the main criteria of the standard for passive houses are as follows:- The energy demand for heating (Qh) must be equal to or less than 15 kWh/m²a
- The energy demand for cooling must be equal to or less than 15 kWh/m²a
- The primary energy consumption for heating, cooling, sanitary hot water (ACS) and electricity must be equal to or less than the result of the following formula: 120 kWh/m2a + [(Qh – 15 kWh/m2a) × 1.2]
- The building's exterior envelope must have an airtightness n50 ≤ 0.6/h
- The energy demand for heating must not exceed 16 kWh/m²a
- The energy demand for cooling must not exceed 25 kWh/m²a
- The frequency of overheating (25ºC) will be less than 10%
- The thermal transmittance (U) of the construction elements must comply with the following standards:
- In opaque elements in contact with the outside air (except for the roof) it must be less than or equal to 0.15 W/m2k
- In the roof, it must not exceed 0.13 W/m2k (for terraces, 0.15 W/m2k)
- In opaque elements in contact with the ground and unheated basements, it must comply with the following formula: f × U ≤ 0.15 W/m2k (where f is the ground reduction factor in the Ground sheet of the Passive House calculation program, PHPP).
- In windows, the transmittance must be less than or equal to 0.85 W/m2k
- When controlled ventilation is carried out, the efficiency must be equal to or greater than 75% and the electrical efficiency of the ventilation system must be equal to or less than ≤ 0.45 Wh/m3
- The limit value of air tightness must be n50 ≤ 1.0 h-1 and the target value, n50 ≤ 0.60 h-1
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