INNOVAL

Objectives

The major objective of Reunion Island is to achieve energy independence by 2025. However, population growth and rising living standards have led to a rapid increase in the energy demand which is the current issue facing this island. In addition, the island is heavily dependent on fossil fuels from which the greater part of its electricity is produced. This is the reason why solutions have to be found.

The construction sector in Reunion Island represents 85% of the electricity demand. For example, on average, an office building consumes 330 kWhep/m²/year; hence, the need to build low-consuming buildings. Moreover, the standard office buildings need to be based on the principles of bioclimatic design, because a lot of energy is wasted on account of the oversizing of the air conditioning and the lighting systems.

These are the reasons why, regulations about building performance such as RT2A DOM or RT 2012, have been established to reach this goal. Moreover, specific labels such as PERENE have been implemented to enhance building design. The project “PREBAT Reunion”, initiated by the French Agency of Environment and Demand Side Management “ADEME” which aims to reduce energy consumption in tertiary buildings in Reunion Island, is also a way to promote the construction of energy-efficient buildings. As part of this project, the intended INNOVAL target was to reach a level of energy consumption equivalent to 30 kWh/m²/year.

The INNOVAL design was based on the following architectural principles:

Passive design

First and foremost, the customer INNOVAL requested the architect to create a building based on Feng-Shui principles. That is the reason why all elements of the building have been chosen and designed to respond to this demand. For example, one part of the building is oriented in the direction of the mountains in the north and the other towards the south. Moreover, there is a planted patio, between the two blocks, which creates a microclimate around the building by decreasing the air temperature. They have chosen to plant several species of broadleaf trees because they create shadow during the summer and they lose their foliage during the winter period.

Secondly, whereas in Reunion Island, most buildings are built with concrete, the structure of INNOVAL is composed of wood and the walls are well insulated with several layers of materials (wood, air, rock wool and zinc roofing). Consequently, the building has a very low inertia, avoiding the loss of thermal energy. This type of building is uncommon in Reunion Island. Besides, these materials like zinc and wood are recyclable materials, therefore, they reduce the impact of the building on the environment, especially when the time comes for demolition.

One of the goals was to create natural ventilation everywhere in the building. Nevertheless, at le Port especially in the area where INNOVAL is located it is difficult to predict a specific wind direction, that is why, the architect decided to put a lot of openings on all facades.

Then, to promote daylighting all rooms open onto the outside. Protection from the sun already exists, as several trees have been planted in strategic locations around the building. In addition, mechanical protection such as solar shading with angle blades operating like shelf lights prevent the glare effect due to the direct sunshine by reflecting the light onto the ceiling and thus enhancing daylighting. Moreover, some windows are embedded in the wall itself, therefore the thickness of the façade acts as a sunscreen.

Cooling system

The hot climate at Le Port led the team in charge of the INNOVAL project to prepare a cooling strategy for different seasons. During the winter, natural ventilation is sufficient to cool offices and during the mid-season between the winter and the summer, natural ventilation is completed with ceiling fans. However, during the summer, natural ventilation coupled with ceiling fans are not sufficient, consequently, air conditioning has to be used. In buildings in Reunion Island, a significant percentage of the energy consumed is due to air conditioning, therefore, the air conditioning system selected here is an efficient one with a Variable Refrigerant Flow ensuring reliability and energy savings. Moreover, a software tool automatically regulates the power of cooling in relation to office use. Finally, while in Reunion Island, people are used to cooling below 24 °C, the air conditioning of the building cannot cool below 26 °C which is adequate with ceiling fans and natural ventilation. Indeed, with the assistance of ceiling fans, the felt temperature is reduced by 5 °C allowing a final felt temperature of 21 to 22 °C. In order to optimize the refrigerated unit power, the temperature adjustment consists of applying a difference of 5 °C between the outside and the inside. For example, if the outside temperature is 34 °C, the temperature adjustment will be 29 °C. All these choices in operation have led to a decrease from 100 kW to 30 kW in the power required by the refrigerated unit.

Lights

The installed lighting density for artificial lighting is lower than that of a standard building. Indeed, highly efficient artificial lighting (6 W/m², 218 Btu/ft²) is used. Dimmable T5 tubes with electronic ballasts are provided for open office spaces and common areas. The LEDs are used as spotlights and for outdoor lighting. Finally, individual offices have desk lamps rather than ceiling fixtures, operating automatically in terms of brightness and presence and providing indirect lighting. All of these systems are in line with the lighting of the work stations which is from 200 to 400 lux.

Data processing

Desktop consumption is mastered through electrical plugs linked directly to occupancy schedules, the widespread use of laptops and the suppression of a centralized wavelength network. Moreover, centralized networks operating constantly under load with poor performance are replaced here by battery-powered laptops. Besides, the consumption of the servers can represent as much as 50 to 65% of the total consumption. In a very low consumption building, as in our case, it stands at 45%, as all the servers (virtual servers, blade servers and low-consuming servers) are installed in the same air-conditioned room in order to reduce heat inputs in offices.

Energy management and monitoring

The performance of a building cannot be perennial and sustainable unless each user is personally committed. The company strategy is based on efficient management of these systems which can be summarized by its motto "Use what you need, where you need it, when you need it".

On the one hand, this approach focusing on the creation of sober and efficient buildings is based on four principles:

“Measurement is the key to reducing consumption”

The lighting and cooling systems are managed automatically by a server, which receives the data sent by the various presence and light sensors according to occupancy schedule.

There is a real-time display of both individual and overall consumption by area, which allows each employee to understand its impact and contribution to the targets.

A common sense booklet was provided to train, inform and involve all the occupants.

On the other hand, conducting a survey about the energy consumption was essential for the management of COREM in order to address the problem, especially from a human perspective. That is the reason why, an energy manager was designated, whose role was to implement a system edited by TEEO, which provides knowledge about the overall energy consumption (electrical, water consumption and so forth). The aim is to render the information more accessible, hence, the occupants in the building can access the data on a home screen where they can perceive the consumption per month or day, the distribution of the different types of consumption, the consumption per office and the avoided consumption of CO2. Thanks to this posting, managers also make occupants aware of their energy consumption. In addition, managers or technicians also have easy access to data: for managers, data is sent to their phones and for the energy managers and technicians, the data is sent and posted on an internet portal allowing easy access without software.

For information, TEEO was developed in Reunion Island in 2009, now it is considered to be a major component of energy management following two years of research and development.

Lessons learnt

Current feedback after more than a year of operation, has revealed that the main problem is linked to the use of air conditioning, especially after the summer period because the occupants have become accustomed to it. Consequently, the main problem is not a technical problem but a human issue, reminding us of the importance of the occupants being actively involved in energy management.

Besides, it has been proven that the energy management system is useful. Indeed, it allows one to target malfunctions immediately: for example, when the software was first installed, abnormal consumption of water was detected. After analysis it turned out that it came from an incorrect setting of the automatic watering system which worked twice as long as necessary. This simple readjustment led to a saving of €540 per month.

Finally, the principle lesson learnt is that the specifications of a building are essential. Indeed, at the beginning, the ground floor was designed for temporary activities because this is the place in the building which is the most restrictive in terms of climatic conditions. However, for logistic reasons, there are now offices on the ground floor and occupant dissatisfaction with their work place is common, so the air conditioning and lighting are over-used leading to an increase in energy consumption.

Conclusion

To conclude, the establishment of an energy management system allows an energy saving of 8 to 15%. Moreover, the energy management of COREM has been certified by the ISO 50001 standard: “Energy management systems” which gives organizations the requirements for energy management systems. Thanks to the application of this standard, they can increase the value of the “White certificates”, a measure taken in environmental policy in order to encourage organizations to save energy, two-fold. Briefly, the more an organization saves energy, the more it obtains certificates which can be resold to their suppliers. In addition, the implementation of an energy management policy actively participates in verifying the smooth conduct of the installations. Furthermore, INNOVAL formed part of the 1000 projects selected in the context of the low-consuming buildings project “PREBAT Reunion” launched and managed by ADEME and the Regional Council in Reunion since 2006 and which rewards buildings which have the ambitious purpose to reach an overall level of energy consumption lower than 60 kWh/m²/year.

In figures, the current consumption of the building since its commissioning in May 2011 is 2.9 MWh/month. In 2012, the overall electricity consumption of the building reached 71kWh/m². This result seems to be far from the expected result of 30 kWh/m²/year, nevertheless, if we remove the electricity consumption due to the servers which represents 45% of the overall consumption, given that COREM is a company in the field of electronics, the electrical consumption falls to 38 kWh/m². Moreover, in Reunion Island, for a typical building of this type, the consumption is approximately 140 kWh/m²/year which means a decrease by a factor of 3.

Finally, even if the climatic conditions at Le Port are challenging especially because of the high temperatures, INNOVAL is the proof that the construction of a building without excessive energy consumption, especially one by using air conditioning, is possible in tropical zones.