ENERGY SAVING MEASURE #1: RAMEAUX
The Energy Saving Measure followed in RAMEAUX concerns the renewal of an energy contract with an energy provider including performance objectives regarding energy consumptions, this performance is supported a profit-sharing system with the provider.
The main evolutions in the new contract include:
– New prices negotiated on the gas price provided.
– A new management and maintenance contract with performance objectives on the energy consumptions and profit-sharing clauses (based on a consumption objective for the heating period – «NB»). The energy provider is completely responsible for the maintenance and efficiency of the heating system.
– The total guarantee plan for the replacement of the heating equipment.
– a complementary modernization plan with a list of possible energy saving measures that may be realized over the long term (including expected savings and costs for investment).
The consultation for a contract expert employed by Auvergne Habitat in order to help the SHO to renegotiate the contract is under 10 000 EUR for the whole stock of the company.
The objective of the optimized ESM is assess the benefits of the profit-sharing contract for the tenants and the SHO identify and quantifying actual energy savings obtained thanks to a regular follow-up of the maintenance interventions made by the energy supplier on the heating system. This process has been implemented on the RAMEAUX building, which is representative of the main typologies of the Auvergne Habitat housing stock with a performance of 137 kWh/y/sm (French Class C).
In order to complete this objective, the Implementation of a weekly on-site visit by the energy provider and heating system manager has been implemented to compare the objective of consumption and the actual energy consumptions.
The monitoring for this follow-up (and the corrective actions implemented) allows to assess the impact for the interventions implemented by the service provider.
This experience on Pilot Site has shown that the maintenance contract is efficient. We can note that the real consumptions (normalized with the heating degree days) index is mostly below the targeted contractual objective (that already ambitious) but varies during the heating season between +12% and -20%. We observe that in 2012 consumption was above target (+4.5%), but in 2013 the efforts of the operator implemented within the AFTER project allowed consumption to be slightly lower (-0.8%) to the target (which had not been changed compared to 2012).
Calculating the energy impact of these savings (based on the HDD-parameter included as an objective in the contract between Auvergne Habitat and its energy supplier) 31,02 MWh have been saved thanks to the implementation of the optimization solution.
These savings represent a potential improvement of exactly 5% regarding the year 2012.
ENERGY SAVING MEASURE #2: BERGSON
Auvergne Habitat has carried a special attention to the ventilation issue in its new refurbished building BERGSON with very efficient external thermic insulation and an energy consumption of 102 kWh/year/sm.
Regarding the performance before (2009) and after the refurbishment (2013), the refurbishment helps to save approximately 25% of energy regarding the existing energy consumptions for heating and hot domestic water (338 MWh – according the contractual-HDD included in the contract between Auvergne Habitat and its energy supplier).
Using its past experience on the Mechanical Controlled Ventilation systems (MCV – working continuously), the SHO identified that MCV is often costly in terms of electric consumptions and creates thermic loses (especially in highly insulated buildings).
As a consequence, Auvergne Habitat has chosen a new ventilation system based on Natural Hybrid Ventilation NHV).
NHV is a compromise between natural ventilation and mechanical ventilation. The objective of the system aims at saving energy consumptions of the ventilation auxiliaries (such as the motors). The NHV uses the wind and the pressure effects on the facades and extractors and the difference between indoor and outdoor temperature to regulate the ventilation system.
The mechanical help is used when natural indicators are insufficient to manage naturally the fresh air renewal. Timers are also activated at some key hours (such as the morning showers and the kitchen time at the end of the day) in order to support the natural ventilation flows and to enhance its efficiency when needed.
The total budget for the implementation of VNH of BERGSON was about 102 000 EUR (less than 1000 EUR/dwelling). This cost do not represent significant increase regarding a classical mechanically ventilation system.
The objective of the testing is to compare (thanks to additional monitoring) two ventilation columns in the building: one ventilation column is equipped with a classic Mechanical Controlled Ventilation (the mechanical help being active all time) ; one ventilation column with a Natural Hybrid Ventilation VNHy©. Relevant indicators will include heat loses, electric consumptions, and temperature/humidity/CO2 emissions. The second step aims at adapting the settings for NHV with the first results: adaptation of the working hours for the system, assessment of the link between the working time of the ventilation system to several parameters (e.g. hygrometry).
The total amount for the monitoring of the two different systems and the final justification for Natural hybrid Ventilation system is about 17 000 EUR (approx.. 110EUR/dwelling).
The savings are estimated on BERGSON can’t be consider as a general approval. Nevertheless we can reach the following conclusions, Natural Hybrid Ventilation represents potential savings both for electric consumptions for ventilation and regarding thermal loses due to the ventilation of the building. Compared to the MCV system these savings have been estimated for the heating season: 7,450 MWh for electric consumptions and 11,832 MWh for thermal loses. The corresponding amount is optimizing the savings obtained thanks to the refurbishment about 6%.
ENERGY SAVING MEASURE #3: AIGUILLADE
The main objective of this testing is to optimize the performance for a refurbished building connected to a district heating network.
The AIGUILLADE building has been recently refurbished in the AFTER project with an important increase of its energy performance (refurbishment of the roof insulation, external thermic insulation from no insulation to a façade with external thermic insulation of polystyrene expanse (120 mm / R = 2,43 m2.kW) ; windows replacement from wood simple-glazing to PVC carpentries with double-glazing, etc.) Refurbishment is mainly dedicated to the improvement of the heating consumptions thanks to the improvement of the general insulation of the building shell.
L’Aiguillade is equipped with a district heating system since 1965. The district heating system has been renovated in November 2012 with a new wood boiler changing the energy mix. The energy mix is now 80% wood-20% gas.
The energy savings associated with heating established on the HDD basis included in district heating contract (2516) permit to measure the difference between the baseline period before refurbishment (2009 – the year which
Measuring the difference between the normalized consumptions before and after the refurbishment we obtain 580,512 MWh of energy savings representing a total percentage of 43% of savings concerning heating.
The optimization implemented during the AFTER project is not based on the optimization of the energy impacts for this refurbishment. It is more based on the optimization of its economic impacts for the SHO and the tenants.
In the old subscription contract, before 2010, a proportional part of the price for heating was calculated using the surface of the building. This pricing was not an incentive to implement energy refurbishments. Since refurbishments do not change the total surface of a building, it wouldn’t impact this part of the price. It would be saving energy, but not money! The implementation of this calculation method is an important change in the new contract negotiated by Auvergne Habitat.
In the new subscription contract, this proportional part is calculated using an indicator: the «average power demand». This APD is based, not on the actual consumption of a building, but on its theoretical “need for energy” (both for heating and domestic hot water).
The savings regarding the price for energy (included in the district heating contract as a fix part) equal to 22 518 EUR saved per year thanks to lowest energy consumptions for the building after refurbishment.
The proportional part calculated thanks to the average power demand equal to 12 315 SAVED per year. The heating consumptions and the savings linked to the refurbishment are fully reported in the energy bills of the tenants. The final average yearly energy savings for every one of the 126 dwellings is about 276, 45 EUR thanks to the renegotiation for the district heating subscription.