Designing and constructing net zero energy buildings is complex and requires multiple approaches, starting with a bioclimatic strategy that is progressively refined through studies and checks throughout the project.
Although a building’s passive performance strategies and the bioclimatic approach always share the same foundations, their definition may vary from one project to another depending on the location, site characteristics, and the client’s needs.
In this regard, we begin by defining a bioclimatic strategy, which is verified together with an energy-efficiency consultancy that quantifies each value based on the design, the construction system, and the selected materials, and applies them to a specific climate zone.
This is known as the energy demand study: an extensive document that assesses each loss and gain across the building’s different elements and allows us to make decisions to optimise its performance.
To deliver net zero energy buildings, we start from the principles of passive architecture:
The aim is to reduce energy demand to the minimum and cover the remaining demand with renewable energy sources. In this way, we can ensure net zero energy buildings and, in some cases, buildings that generate more energy than they consume.
Blower Door test to ensure airtightness
Energy efficiency requires a high level of control over heat exchange between indoors and outdoors. When we can decide when we want—and when we do not want—to capture heat inside our building, we achieve full control over its temperature, and it is important that this temperature is not lost due to poor insulation or through air leakage.
Insulation is controllable: we can choose the thickness and ensure full continuity throughout the envelope through the definition of construction details and rigorous site supervision.
However, airtightness is more difficult to control on site, and we need a specific test to ensure that a home does not have energy losses due to small points or non-airtight joints that may be imperceptible to the naked eye.
To do so, we carry out the Blower Door test—an airtightness test—which checks a building’s air tightness by creating positive and negative pressure inside it, detecting leaks using thermal cameras or smoke machines. Here you can find all the details about the blower door test for Passivhaus certifications.
Based on the test—which can be carried out several times throughout the construction process—improvements are made to non-airtight joints or seals, and the results are measured again until the airtight performance of our building is optimised.
We carry out the test on those buildings where we decide to reach high efficiency standards, without this necessarily implying energy certification.
A building being airtight does not mean that windows cannot be opened; rather, it means ensuring that, if the windows are not opened, indoor air quality is guaranteed at all times.
Indoor air renewal is carried out through trickle ventilation in windows or doors, or through mechanical means such as air inlets or heat-recovery ventilation.
In fact, the air quality of airtight buildings in terms of CO2 and the build-up of toxins or pollutants from external sources (air pollution) or internal sources (toxic emissions from furniture, paints, fabrics, or cleaning products) has been proven to be much healthier in an airtight home with controlled air renewal than in a conventional home.
BUILDING CERTIFICATIONS
Although working with a specialist team in efficient net zero construction ensures success, it is true that in certain cases—such as housing developments, corporate buildings, or private homes designed with the intention of being sold in the short term—it may be necessary to have a certification that inspires confidence in future buyers.
In these cases, we work with three of the leading certifications which, in our view, provide the greatest value and are the most up to date not only in terms of energy efficiency, but also in terms of a zero ecological footprint and the health and wellbeing of occupants.
These are Passivhaus certification, LEED certification, and WELL certification.
To work with additional certifications, please contact us.
CERTIFYING A PASSIVHAUS BUILDING
Passivhaus certification was developed by the Passivhaus Institut in 1988. Its name comes from the concept of passive architecture, so the standard considers the local climatic conditions of the project site and sets different limits depending on the country. To assess a building’s energy performance, it establishes quantifiable limits for heating demand, cooling demand, and total primary energy consumption, as well as a maximum number of air changes per hour. A certifying specialist can validate the calculation based on the construction documentation, and a Blower Door test is required once construction is complete. There is a database called the Passive House Database, which allows you to filter and discover all certified buildings on a map.
CERTIFYING A LEED BUILDING
LEED certification (Leadership in Energy and Environment Design) was developed by the US Green Building Council in 1993. The rating system is based on a comparative label that analyses sustainability and market factors across different categories, with a focus on energy and ecology. Documentation must be submitted for verification after the design phase and again during the construction phase to confirm that the project has been executed in accordance with the standards set out in its reference guide.
CERTIFYING A WELL BUILDING
The WELL Building Standard certification was developed by the International WELL Building Institute (IWBI) in 2014 and refers to the concept of wellness. It consists of a scoring system that measures the characteristics of built spaces that impact occupants’ health and wellbeing, becoming the first system focused exclusively on users’ health and comfort. In Spain, the Instituto Tecnológico de Galicia is responsible for adapting the standard to the conditions and regulations of our country.