Net Zero Energy Buildings (NZEB) can assist with the global push to reduce energy consumption and are desirable in an increasingly eco-conscious world. However, the practical steps to bring NZEBs from design to reality can be made arduous with the wrong products and limited expertise. As NZEBs become an essential component in the legislative and cultural shift towards a sustainable built environment, dynamic products that save us both time and effort could be the difference between meeting the global target of reducing energy consumption in a limited time frame and falling short. 

How is the process of NZE achieved?

• Address the building envelope – take a fabric-first approach to reduce energy demand from HVAC systems in the long term, with little to no maintenance

• Employ energy efficiency measures – reduced remaining demand further with measures such as daylighting, LED lighting, natural ventilation and heat recovery systems 

• Supply remaining demand with renewables - use non-polluting energy generation, such as wind or solar, to eliminate reliance on fossil-fuel generated energy

It takes a balance between insulation and generation to achieve Net Zero Energy Buildings, and by following this process, NZE should eventually be possible for all buildings. For buildings to achieve NZE, they should be aiming to reduce their energy use by around 60-80%.  

What is a 'fabric first' approach?

A ‘fabric first’ approach refers to the ‘building fabric' — the physical materials which separate the indoors from the outdoors. Frames, external structure, windows and insulation all come under this umbrella. 

A 'fabric first' approach prioritises heat conservation and involves maximizing the thermal efficiency of a building’s external envelope before defaulting to the use of mechanical appliances. For example, good insulating materials should be installed before considering electrical heating, as this will boost the effectiveness of the system and help to conserve energy use. A ‘fabric first’ approach should centre around increasing air tightness, preventing thermal bridging, and enhancing insulation, natural ventilation, and daylighting. 

What are the benefits of a 'fabric first' approach?

Taking a fabric first approach is widely recognised as a highly beneficial step in ensuring an energy efficient building, whether you are refurbishing an existing building or constructing something new. Benefits include: 

• Creating a highly insulated building envelope with carefully constructed junctions to minimise air-leakage and unnecessary heat loss/gains will help to reduce demand on HVAC (Heating, Ventilation and Air Conditioning) systems, and potentially the size required

• The envelope will then keep delivering energy savings over the long-term with little or no maintenance

• When buildings are properly insulated, there are numerous health benefits that arise from an increased thermal comfort and better indoor air quality

• Reducing the initial energy demand of the building makes it more viable to meet the majority of the remaining demand with renewable technologies, either through onsite generation or conscious energy procurement

What needs to be considered when constructing a NZEB?

1. Early consideration in the design phase

From the very beginning of the design process, the concept of NZE must be central to the architect’s initial plans. Design features that will reduce energy consumption include double or triple glazing for windows, natural ventilation, air sealing and enhanced insulation values. 

2. The location of the building

This can affect both its energy demand (e.g., buildings in exposed locations may require more heating to keep them comfortable in comparison to a building in a more sheltered and built-up area) and its ability to access sunlight for daylighting and solar energy generation.

3. The orientation of the building

In the global north, it matters what aspects of the building are south facing, to ensure the efficacy of solar panels and daylighting systems. 

4. The size of the building

Broadly speaking, the more compact a building is, the easier it is to achieve high energy efficiency, because less energy is needed to heat, cool and light it. 

5. The installation of renewable energy

Energy is, of course, still required to power the building. In this case, buildings are reliant on renewable energy sources such as solar and wind power, hydroelectric, biomass and heat pumps to remain net zero energy. 

Net Zero Retrofits

Retrofitting involves adding new renewable and efficient technologies to existing buildings to reduce grid energy consumption. To reach the UK government’s target of net zero energy by 2050, it is essential to upgrade the energy efficiency of millions of buildings. As many as 80% of the buildings that we will need in 2050 already exist or are in planning, therefore a huge proportion of these buildings would need to be retrofitted to make this target attainable. Retrofitting old or poorly insulated buildings sidesteps the energy consumption that occurs during the demolition process and is a markedly quicker and cheaper process than rebuilding new properties. The other 20% would be new builds, which optimistically will have an inbuilt NZE ethos that spotlights the use of renewables and smart insulation in the bid to meet global carbon targets.