As some of you already know, Passivhaus architecture aims to save up to 90% of energy consumption and carbon emissions derived from construction without sacrificing maximum comfort. The Passivhaus standard is the most demanding in terms of energy efficiency in the world and guarantees that the performance of the constructed building corresponds to the theoretical design values. Unlike other responsible construction methods, Passivhaus does not seek to achieve energy self-sufficiency, but rather to consume the minimum necessary energy.
As we saw in previous articles, the standards for Passivhaus buildings are 5: (1) Ventilation with heat recovery, (2) Thermal insulation, (3) Airtightness, (4) Thermal bridge-free design, (5) Optimal windows.
Passivhaus is a voluntary energy certification standard for new build or renovation projects. To accredit compliance with these criteria, there are two types of certificates:
Passivhaus Certificate, for new construction. Its standards are:
- The heating energy demand (Qh) must be less than or equal to 15 kWh/m²a.
- The cooling energy demand must be less than or equal to 15 kWh/m²a.
- The primary energy consumption for heating, cooling, domestic hot water (DHW) and electricity must be less than or equal to the result of the following formula: 120 kWh/m2a + [(Qh – 15 kWh/m2a) × 1.2].
- The external envelope of the building must have an airtightness n50 ≤ 0.6/h.
Furthermore, there is a subclassification within the Passivhaus certification: Classic, Plus and Premium. The Classic certification is for buildings that do not generate renewable energy. On the other hand, for the Plus certification, at least enough renewable energy must be generated to compensate for the building’s consumption. To obtain the Premium classification, it is necessary to generate between 4 and 5 times more than what the building consumes.
EnerPhit Certificate, for renovation projects.
- Heating energy demand cannot exceed 16 kWh/m²a.
- Cooling energy demand shall not exceed 25 kWh/m²a.
- The frequency of overheating (25ºC) shall be less than 10%.
- The thermal transmittance (U) of the construction elements must meet the following standards:
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- For opaque elements in contact with outside air (except the roof), it must be less than or equal to 0.15 W/m2K.
- For the roof, it must not exceed 0.13 W/m2K (for terraces, 0.15 W/m2K).
- For opaque elements in contact with the ground and in unheated basements, it must comply with the following formula: f × U ≤ 0.15 W/m2K (where f is the ground reduction factor on the Ground sheet of the Passive House Planning Package (PHPP) calculation tool).
- For windows, the thermal transmittance must be less than or equal to 0.85 W/m2K.
- When controlled ventilation is carried out, the efficiency must be greater than or equal to 75% and the electrical efficiency of the ventilation system equal to or less than ≤ 0.45 Wh/m3.
- The limit value for air tightness must be n50 ≤ 1.0 h-1 and the target value, n50 ≤ 0.60 h-1.
Certification and Audit
The only entity authorized to certify is the Passivhaus Institute. The process begins with the audit from the design phase through to the construction phase. The certifier must confirm that the work is being executed as planned and designed in the initial phases, reflecting correct modeling in the PHPP (a tool developed by the Passive House Institute).
For the audit, a series of documentation must be submitted, including architectural project documents, photographic resources showing how the requirements were executed, the final certificate of the Blower Door test, the results of the ventilation system commissioning, and a letter signed by the technician responsible for the Site Management indicating that the work has been executed in accordance with the project.
Arquifach: Architecture Studio Alicante
If you are thinking of building a custom home that respects the environment while maintaining maximum quality and comfort, contact Arquifach, Alicante architecture studio. Benefit from no-obligation advice from a great team with over 40 years of experience.
