In recent years we have witnessed increasing awareness of climate issues, both among individuals and governments. The focus is on reducing the climate-changing impact of human activities, in terms of emissions and consequently primary energy consumption, relating to both industrial and other activities.
In this regard, the European Union has set the goal to reduce primary energy consumption by at least 20% by 2020, through Directive 2010/31/EU, whose scope is broad and covers different sectors. However it is the residential sector that is most affected: contrary to what we might think, households make the same contribution as industry in terms of primary energy consumption, and consequently emissions of climate-changing gases.
The figure below illustrates that around 50% of our energy consumption can be attributed to these two sectors, with transport accounting for 33%.
In order to implement the changes needed to achieve the objectives defined by the European Union, efficiency in the residential sector is essential. Consequently, there is much more attention to NZEB (Nearly-Zero Energy Buildings). More than just an acronym, this is an actual definition agreed on by all the participating countries, specifying the technical requirements of new buildings. Indeed, starting 2020 all new residential buildings must have an energy impact, expressed in kW/m2/year, that is as close as possible to zero. To set the example, all new government buildings have needed to comply with these new regulations since 2018.
So what do the NZEB requirements involve?
They take into account all of the state-of-the-art technical solutions in terms of high energy efficiency. Indeed, when constructing a new building, technical, economic and environmental feasibility aspects must be factored into the design, adopting high-efficiency solutions such as:
These solutions are adopted for space heating, domestic hot water production, air-conditioning, ventilation and air handling in general. To ensure optimal, or optimised, management of the available energy resources, weighted control of the building’s technical systems is required. Such control, which can be customised to varying extents depending on the user, is based on different environmental and system parameters. Where possible, modulating operation of the units is preferable, so as to reflect the thermal load as closely as possible. Interfacing together several modulating systems, such as heat pumps combined with large ventilation systems, is complex but certainly economically beneficial.
Depending on the country where new systems designed to help achieve a NZEB are installed, economic incentives may be provided to help users recoup the cost of the technical solutions adopted. It is also useful to have systems available for monitoring energy consumption, as well as sensors for monitoring environmental parameters, so as to understand the building’s effective energy consumption. Moreover, wireless monitoring can also be adopted, with the possibility of continuous remote monitoring, combined with a smart interface for viewing the data.
According to Directive 2010/31/EU, these types of solutions are intended for a wide variety of applications. They can be briefly summarised as follows:
Single-family houses of different types
Hotels and restaurants
Wholesale and retail trade services buildings