Merit order of energy efficiency actions in tertiary buildings

In France, the plan for energy renovation of the tertiary sector consists in a progressive reduction in finale energy consumption over the coming years until 2050. In July 2019, French government, released a decree that defined cut-off thresholds for all existing and new buildings with a tertiary activity area of ≥ 1,000 m². All branches (offices, education, health…) are required to take action regarding their building performance (insulation, windows, thermal bridges etc.) and also their equipment (HVAC, lighting…).

However, the initiative faces some challenges. First, the sector presents significant disparities that slow the formation of a market-wide structure. Furthermore, there can be resistance from building owners due to the high costs that might be involved (particularly for old buildings).

Our study shows that there are economic and environmental opportunities in following of a renovation roadmap.

Proving this point requires measuring the economic impact of energy efficiency actions and conducting a precise classification of renovation actions that are combinations of energy-efficient systems and of passive technologies such as insulation. Because these cost-effectiveness issues depend on many aspects linked to the building, it leads to carrying out sensitivity analysis not only regarding the building activity, architectural features, thermal behavior and age, but also external aspects such as local climates.

For this article, the study will involve :

1. Carrying out a situational analysis of the French tertiary sector buildings and identifying tertiary branches with the largest potential of energy savings.
2. Modelling scenarios for these identified branches to measure the energy gains resulting of diverse energy renovation actions.
3. Doing a merit-order of renovation actions with estimations of global operating costs (OPEX), capital expenditures (CAPEX).

Consequently, energy system types (heat pumps, hybrid heat pumps, condensing gas boiler, district heating/cooling network, controlled mechanical ventilation) will be compared to one another according to their responses to the heating needs of each building type, but also to air-conditioning needs, and air exchange demand.

We will also see that regulatory guidelines can favor some technologies and change the overall rankings of technologies.

About the CO2 value:
As one of the main mechanisms in the fight against climate change consists in putting a price on carbon, our study evaluates the carbon pricing based on a averaged abatement costs calculation. This indicator will be defined as the additional CAPEX and OPEX that are required to renovate a gas system and to avoid the emissions of a ton of CO2.