When we talk about energy efficiency in buildings we usually refer to the set of procedures that lead to the building consuming less energy, but the fact of the matter is determine how far it is possible or reasonable to go.
State regulations inspired by the Directive of energy efficiency tend to take as a reference what is called "optimal cost" consisting of investment costs are assumable in relation to the economic benefits that entails the lowest energy consumption (optimization).
Note: You can consult the application of the methodology of «optimal cost» in the EU countries from HERE in English.
Even though viability is important economy, this is not the only criteria possible and could try to reduce the energy consumption of the building until it is practically nil or that the impact resulting from the construction and operation of the building is minimal (minimization).
It is evident that according to the different criteria that adopt as a reference, the levels of ambition in the obtaining energy efficiency will also be different.
In this article we will try to evaluate for a building given, what is the level of ambition that these provide different criteria and we will show that the most commonly used, which is energy optimization, leads precisely to be the least ambitious and we would do well not to consider it as the preferred criteria.
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In this case, a building is considered multi-family between houses composed of PB + 4 floors with a total of 16 homes with an area conditioned of 1282 m2 (only the houses are considered conditioned)
The following image shows the building considerate:
CHARACTERISTICS OF THE BUILDING:
The first step is to evaluate the amount of energy final consumed by heating, cooling systems including the associated consumption of the circulators of fluids.
In both cases, it can be seen that within the levels of isolation considered in the study (between 0 and 22 cm) the consumption decreases as the availability of isolation, and, therefore, it will always be positive to increase insulation if you want to minimize energy consumption.
The “total cost” is the sum of the costs derived from the investment in insulation and the costs of operation of the building.
The results are reproduced below:
It shows that, in this case, if there is a value which provides a minimum total cost and which levels of lower or higher insulation lead to an increase in cost.
It is also appreciated that the higher levels of insulation, represent negligible total cost increases. While lower insulation levels provide considerable cost increases.
The commonly called “optimal level” of insulation, is actually the “minimum level” below which no we should never be to not include in cost overruns important.
To assess the environmental impact due to the incorporation of the insulation, the Environmental Declarations of the Products (DAP / EPD) brought into the building and it has been considered the greenhouse effect (GWP) of each case throughout the life cycle.
Remember that we have an extensive article on how to calculate the environmental impact of a building and what programs written also by Josep Sole.
In a similar way to how energy consumption has been translated at operating cost, the potential effect has been evaluated greenhouse depending on the type of fuel used. The Results are summarized in the following graphs.
As was the case with energy consumption, in this case, the total environmental impact throughout the entire life cycle is reduced with increasing insulation level without find, at least within the studied environment, a value limit that causes an increase in the environmental impact of the building.
Consequently, contrary to what some claim, no In no case should the amount of insulation be limited to install in the building for environmental reasons.
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