How to reduce the energy consumption of our buildings

One of the main causes of climate change is the excessive energy consumption of our buildings. In cities, the residential sector is responsible for approximately 30% of direct emissions, according to Deloitte's analysis in their report The Future of Sustainable Cities: Urban energy transition to 2030.

Much of Spain's housing stock is made up of old buildings that do not meet energy efficiency standards and require significant investment. In total, it is estimated that two-thirds of buildings require refurbishment and maintenance because they do not meet energy efficiency and thermal insulation standards.

Where is energy going in the residential sector?

The breakdown of consumption in cities shows that climate is the most important factor in explaining energy consumption and emissions in the residential sector.

• Heating and hot water account for the largest share of energy consumption in a household (60-70%). In cities with cold climates the heating needs are greater and a home in this kind of climate can consume twice as much energy as a home in a city with a warm climate.
• Air conditioning accounts for less than 5% of energy consumption as, although it involves significant consumption in the summer months, the total hours of use throughout the year are low. In addition, their use in homes is less widespread than that of heating systems.
• Other residential consumption –kitchen, appliances, lighting, etc.- is more consistent in all climates, although their relative weight varies according to the weight of the other consumption.

Difficulties in the residential sector

La Improving energy sustainability in the residential sector faces a number of difficulties: a very diverse housing stock, construction techniques that do not meet energy efficiency criteria, challenges to renovation works due to the significant investment required and the disruption and inconvenience to the life of the people that inhabit these buildings.

Therefore, in order to tackle the challenges of energy sustainability, we need to take a pragmatic approach, analysing each case individually and identifying what measures are most likely to achieve sustainable and environmentally friendly urbanism.

Priority actions in the residential sector

According to Deloitte's report, the key measure that should be taken in this sector is the installation of heating control systems to improve energy conservation. The installation of thermostats and systems that allow users to adjust heating consumption and adapt it to outside temperatures could reduce thermal energy consumption by between 15% and 30%.

Then, depending on factors such as the existing heating in the home, the state of repair of the building, the climate zone and the investment required, heating equipment should be switched for more efficient options, such as heat pumps or natural gas condensing boilers. Heat pump systems are best for reducing energy consumption and emissions in a home, while natural gas condensing boilers are more efficient than conventional boilers and produce fewer emissions.

The next measure in order of priority is the implementation of energy refurbishments. Within this measure, the four most important types of refurbishments are window replacements, which can reduce heat consumption by between 10% and 25%, refurbishment of façades and roofs with layers of insulating material, or comprehensive refurbishment.

Despite the significant reduction in consumption produced by refurbishment (more than 60% heating reduction following a comprehensive refurbishment), another measure to consider is the replacement of appliances for more efficient models with an A++ energy rating, i.e., those with the lowest energy consumption.

In addition, the installation of photovoltaic systems on the roofs of urban buildings or nearby surfaces (patios, gardens, car park roofs, etc.) could be considered to enable residential self-consumption. An increasingly widespread option is the use of organic waste for biomass energy generation, which has increased from 3.2% of energy consumed in Spain to 6% over the last 15 years. The domestic storage batteries in smart homes represent a huge step forward as they allow the storage of surplus solar energy that has been self-generated during the day.

How can energy efficiency be increased in construction?

The buildings that are built and refurbished today will continue to exist beyond 2050, so it is important that we understand that what we do today is mortgaging the future of our buildings. This means that introducing sustainability and energy efficiency criteria into any residential project must be priority.

Some recommendations for city councils and municipal administrations include:

• Defining action plans at the municipal level that require consumption and emissions reductions and air quality improvements to be achieved.
• Setting a target for 100% of buildings to have energy certificates by 2030.
• Launching awareness campaigns to disseminate information to tenants and property owners regarding the measures implemented in the building action plans.
• Establishing a schedule for restricting the marketing of inefficient equipment.
• Promoting the incorporation of energy sustainability criteria into refurbishments that are carried out in buildings as a matter of course.
• Supplementing the Technical Building Code for new buildings to establish restrictive limits on energy consumption, depending on the climate zone.
• With regard to municipal administrations, changing current electrical tariffs so that they act as an effective price signal that does not penalise the adoption of electrical equipment over other, less sustainable options.