Por: Hamilton Ortiz
Dec 13, 2016
Energy Efficiency
The air conditioning system is responsible for a large part of the electricity consumption in retail commercial spaces. In the hottest months of the year, this consumption increases, and the energy bill seems to follow the high temperatures of the season. When the store is not air-conditioned or only has fans, the effect of the variations comes at another end: the thermal comfort for the occupants. In this case, what increases are the demands of employees and customers. Thermal insulation can be a good option, but it is not what is seen in many cases.
This effect is marked by seasonality. So, is it worth simply increasing the installed load of refrigeration and ventilation equipment? The answer is not so simple, and depends on factors such as the level of comfort that a company intends to deliver in its commercial space and the possibility of carrying out renovations in existing stores. For new stores, the potential is much greater during the design phase.
In the context of supermarkets, where another important system is food refrigeration, energy efficiency measures incorporated during the design phase can generate savings of 50% of total annual consumption, compared to a store designed without these concerns.
From the point of view of energy efficiency, passive approaches are always the first option. Walls, windows and coverings separate the internal space from the external environment. Therefore, these components are great opportunities to avoid the gain of thermal energy that we will need to eliminate through air conditioning systems or that will make our occupants uncomfortable.
So we put thermal insulation on everything, right? No. We cannot apply insulation indiscriminately throughout the entire envelope of a retail space for several reasons, including:
– Additional implementation cost;
– Compliance with the brand's aesthetic concept;
– Regional bioclimatic conditions.
The first two factors are decisive in any retail company; cost and aesthetics are issues that the Brazilian market already understands. On the other hand, the characteristics of the climate in the different regions of the country generate the need for a more detailed approach. It is common to design sandwich tiles as the main measure for the envelope in smaller spaces (1,000 to 2,000 m²). In larger sales rooms, between 6,000 and 8,000 m², the solution is usually Face Felt insulation with zipped tiles. However, the type of insulating material and its thickness directly impact the results.
The insulation layer reduces the thermal transmission value (U value expressed in W/m²K). This means that less energy passes through the roof in a given unit of time. Another important characteristic is the Thermal Capacity, which indicates the amount of heat required to vary the temperature of a material by one unit, expressed in J/(Kg.K) in the International System. Combined, these characteristics help us choose the best solution for roof insulation.
Reducing the U value to the extreme may not be the most efficient solution. This is because throughout the day we have temperature variations that can be significant depending on the region of the country, which means that for some hours of the day or night the store can be cooled naturally.
When we over-insulate the building, we prevent it from losing heat at these times. This requires our cooling or ventilation system to continue functioning.
In commercial spaces, there are other important thermal load gains, such as the results of lighting, skylights, openings, equipment and the occupants themselves. We can treat each factor separately, but thinking about holistic strategies allows for better energy performance and savings in the implementation of solutions.
Whether new construction or renovation, the practice of integrated design aided by thermal-energy simulations can achieve significant energy savings that translate into value for companies, obtaining adequate levels of comfort and conferring environmental responsibility to stores.
Does your company prioritize energy efficiency in its stores? Have you thought about ways to reduce energy costs? Want to know more about integrated design or simulation? Contact Mitsidi!