Auberge de jeunesse de Pontivy
The client’s objectives and expectations
Propose improvement solutions for the site primarily aimed at reducing the client’s energy bills.
Our main tasks
First, we carry out an assessment of the building by analyzing its envelope (walls, windows, roof, etc.) and its equipment (heating system, domestic hot water production, ventilation, lighting, etc.). This evaluation begins with a site visit and is then further developed using analysis tools in the design office.
Next, we identify potential improvements for the building, such as wall insulation, window replacement, heating optimization, or ventilation system enhancement. Among these proposals, we select the most relevant ones—those offering the best compromise between energy consumption reduction and minimal investment.
To ensure compliance with the requirements of the Tertiary Decree, which mandates a reduction in energy consumption for buildings over 1,000 m² (as is the case here), we develop several work scenarios incorporating these improvement solutions.
Finally, once the study is completed, we present it to the client with recommendations tailored to their needs and constraints.
Project characteristics
- Total area: 1,200 m² (main building + annex)
- Building envelope
- Walls: Poor insulation
- Lower floor: Poorly insulated, resting on solid ground (work not feasible)
- Upper floor: Average insulation
- Windows and doors: Fair to poor condition
Existing equipment
- Heating:
- Main building: 75 kW condensing gas boiler,
- Annex: Electric radiators,
- Domestic hot water (DHW):
- Main building: 400 L gas water heater,
- Annex: 500 L electric water heater,
- Ventilation:
- 5 single-flow ventilation units,
- Lighting: Average quality,
Annual energy consumption
- Total: 98 MWh/year.
Résultats obtenus
Objectives of the Tertiary Decree:
- -40% by 2030,
- -50% by 2040,
- -60% by 2050.
Energy improvement scenarios
Scenario 1
- Installation of a double-flow ventilation system,
- Interior thermal insulation (ITI) throughout the site,
- Insulation of the upper floor of the main building,
- Replacement of the windows and doors.
Energy savings: -27%,
Investment: €391,500.
Scenario 2 (Scenario 1 + additional improvements)
- Replacement of lighting fixtures throughout the site,
- Optimization of the heating network in the main building,
- Implementation of centralized control for the annex.
Energy savings: -31%,
Investment: €400,900.
Scenario 3 (Scenario 2 + low-carbon solutions)
- Installation of an air-to-water heat pump for the annex,
- Installation of a solar thermal system for both buildings,
Energy savings: -46%,
Investment: €477,100,
Compliance with the first threshold of the Tertiary Decree (-40% by 2030).
We were aware of the urgency of the work, but we didn’t know where to start. Thanks to the audit, we now have a clear view of the actions to be taken.
Pontivy Youth Hostel