Building energy audits: legal requirements and benefits
A building energy audit is a useful tool to understand which energy efficiency upgrades could be implemented to bring the entire building up to a higher level of efficiency, especially in terms of costs and benefits. But in some cases, for both public and residential buildings, carrying out such an analysis is actually required by law.
Published on 26 March 2020
Using an energy audit to conduct a detailed analysis of a building’s energy consumption and waste is useful to understand what can be done to improve the energy efficiency of the building, reducing its energy requirements (and therefore the associated costs) and enabling – if the upgrades are implemented – access to a number of incentives, such as Italy’s conto energia termico scheme (feed-in tariffs) or so-called ecobonus.
Including an energy audit is always advisable as part of any building’s energy efficiency improvement plan, but in Italy it is actually a legal requirement for any public or residential buildings that intend to install, or replace, a boiler with a power output exceeding 100 kW (as set forth by Presidential Decree no. 59 of 2 April 2009). In particular, article 4 of the decree makes an energy audit compulsory for public or residential buildings where the plan is to install a new heating system, to renovate an existing one or to replace the heat generators (where the nominal power output of the system’s firebox is greater than or equal to 100 kW). It’s important to note that the audit must consider both the building and the system, and that it must be conducted before the work is carried out. In addition, the audit must include a financial evaluation of the project costs and the predicted energy cost savings, as well as the investment payback periods and the potential improvements in the building’s energy rating.
However, in Italy energy audits must not be confused with the Attestato di Prestazione Energetica (APE - Energy Performance Certificate). Indeed, the APE is based on a standardised calculation procedure to estimate a building’s energy consumption. The evaluation is usually carried out with the help of specific software, which make it possible to identify the energy rating of a building or property. The energy rating is attributed depending on the annual energy consumption per square metre, calculated according to the performance of the building envelope, the efficiency of the heating and hot water production systems, and the possible presence of renewable energy systems (as set forth by the UNI TS 11300 standard).
By contrast, the calculation used in energy audits starts by collecting relevant data from energy bills, and builds a picture of the actual electricity and fuel consumption. This is then compared with the figures provided by the building energy model, created using simulation software, finally obtaining indicators that can help to identify solutions that could improve the performance through specific enhancements, which may involve the building envelope and the building’s systems (ranging from heating system to internal movement facilities such as lifts, and from lighting to air conditioning systems). The benefit offered by an energy audit doesn’t just lie in the calculation of overall consumption in order to identify the “weak points” in the building’s use of energy, but also in the opportunity to compare various design solutions so as to make an optimum, fully-informed choice that will help to reduce energy consumption, and therefore energy bills. The guidelines for correctly conducting an energy audit have been defined by ENEA, Italy’s National Agency for New Technology, Energy and Sustainable Economic Development, and are outlined in a Manual for conducting energy audits on public buildings, which is also applicable to residential buildings.
The proposed design solutions must compare the types of systems set forth by Ministerial Decree 26/06/2015, which defines the “minimum requirements” for buildings’ energy performance. Centralised heating systems, for example, must be designed so as to employ condensing boilers, gas or electric heat pumps or cogeneration systems. These must always be used in conjunction with individual metering and temperature control systems within every apartment. Heating solutions can also be combined with a system that uses renewable energy sources, such as a solar thermal system, which can be used to produce hot water or provide heating. Therefore, energy audit recommendations can guide everyone – even private individuals – towards making the right choice, leading to a real improvement in the energy performance of a building and to a subsequent reduction in energy consumption and costs, as well as to benefits for the environment as a whole.
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