Parlouër Constructions in Brittany delivers one of the first BBC houses in the region

A VERY LOW ENERGY HOUSE

During the construction of the Milon family home, everything was designed to create a building with a maximum primary energy consumption of 55 kWh per square meter per year*, in order to make it one of the first BBC-Effinergie certified homes in the region. "We decided, in agreement with the owners, to take on the challenge of the BBC-Effinergie label, which, at the launch of the project, was only in its infancy," explains Christophe Parlouër, director of Constructions Parlouër.

To reduce energy consumption as much as possible, the Beg Léguer house has been equipped with several appropriate features: a heat pump (PAC) for low-temperature underfloor heating and domestic hot water, double-flow controlled mechanical ventilation (CMV), large double-glazed windows with reinforced thermal insulation, correctly oriented, and a roof overhang to limit the heat of the sun in summer.

PERFECT AIRTIGHTNESS OF THE BUILDING

The exterior walls of the house were constructed from Xella's YTONG mi335 cellular concrete. With its thermal resistance (R) of 1,82 m²K/W, this structural material is widely used by single-family home builders and is a construction solution perfectly suited to low-energy buildings. When added with added interior insulation, it can achieve energy savings of up to 65%.

"The walls of the house are 32 cm thick, they consist of the exterior wall in mi335 of 20 cm and a glass wool insulation of 12 cm" specifies Mr. Parlouër.

The high performance of a wall made of mi335, in terms of thermal resistance and air permeability, comes from the material itself (cellular concrete with a honeycomb structure contains 80% air) and its thin joint installation principle which increases insulation and eliminates thermal bridges.

“The cellular concrete block also has advantages in terms of implementation. It is easy to cut, which allows for great flexibility of use. In addition, its handling and installation are faster thanks to its lighter weight and thin-joint bonding principle. In addition, it accepts many finishes. For example, on this site we applied PRB facade coating and even wood cladding without any problems,” says Mr. Parlouër.

VERIFICATION OF BUILDING PERMEABILITY BY INFILTROMETRY TEST

Measuring a building's airtightness is mandatory to obtain the BBC-Effinergie Label. The infiltration test makes it possible to detect any airtightness defects in the building and to detect uncontrolled outgoing and incoming air flows (heating losses and cold air infiltration). The main parasitic air flows in a house are the facade and floor connections, exterior woodwork (door sills, etc.), electrical equipment (switches and power outlets), hatches, and elements passing through walls.

"After sealing the house's air inlets and outlets, a blower door equipped with a fan creates a vacuum and allows us to determine the amount of air infiltrating through the walls. This test was successfully carried out in Beg Léguer," says a delighted Christophe Parlouër.

In fact, the measured non-voluntary air infiltration index of 0,5 m3 per m² is lower than the 0,6 m3 per m² required to obtain the BBC-Effinergie label.

WHY A BBC-EFFINERGIE LABELED HOUSE?

"It's important to build sustainably to save energy and reduce greenhouse gas emissions. In addition, the day-to-day benefits are significant, such as thermal comfort, building preservation, hygiene, and health," says owner Christophe Milon. "Our annual heating and hot water costs have been more than halved. There are also significant tax savings, as the 40% tax credit on loan interest, usually reserved for the first year of repayment, has been extended to seven years."