Net Zero Buildings and Smart Glass

In a Nutshell

According to the International Energy Agency, buildings account for 30% of global energy consumption and 26% of global energy-related emissions.

The United Nations Climate Change Conference (COP21) in Paris in 2015 reached a breakthrough agreement to maintain global temperatures within 2°C of pre-industrial levels.

To achieve this, the US Federal Sustainability Plan and the European Union Net-Zero Industry Act have since created initiatives to foster climate neutrality through what is called ‘Net Zero’.

‘Net Zero’ can actually mean two different things in the building sector:

• Net Zero Energy: which balances the energy consumed by a building with the energy produced by onsite renewable sources (e.g. wind and solar power).
• Net Zero Carbon: which balances the emissions of carbon dioxide (and other greenhouse gasses) with their removal from the atmosphere (via carbon sequestration).

Embodied vs Operational Carbon for Net Zero Buildings

In the case of net zero carbon, we are talking mainly about the operational carbon footprint of a built structure – in other words carbon emitted after it is built.

However, we must not forget the embodied carbon that was expended in manufacturing the building materials and components.

The image below shows the ‘pipeline’ of carbon dioxide and other greenhouse gasses across the manufacturing lifecycle:

1. raw material extraction
2. manufacturing of building materials such as cement, steel, aluminum and glass
3. transportation / transit of building components
4. operational building use
5. reuse, recycling and end of life.

Greenhouse Gasses

When we refer to ‘carbon emissions’, we are really referring to all greenhouse gasses that can trap heat in the Earth’s atmosphere.

Greenhouse gasses include:

• Carbon dioxide (CO₂): emitted by burning fossil fuels (e.g. coal, natural gas and oil)
• Methane (CH₄): emitted by livestock, land use and decay of organic waste in landfills
• Nitrous oxide (N₂O): emitted by agriculture, industry, fossil fuels, solid waste and wastewater treatment
• Fluorinated gasses (e.g. hydrofluorocarbons, or HFCs): emitted by household, commercial, and industrial processes
•  

We can see the breakdown of greenhouse gasses, according to the US Environmental Protection Agency (EPA), which shows carbon dioxide as having the greatest concentration (79.7%) in the Earth’s atmosphere:

However the above diagram does not show the potency of each gas.

Global Warming Potential (GWP)

For this, we need to consider the Global Warming Potential (GWP), a weighting factor that shows how much a gas contributes to global warming, with reference to carbon dioxide.

The GWP is an index that measures how much solar infrared a gas absorbs over a given time frame when compared to carbon dioxide.

The following image shows the GWP for several greenhouse gasses over a 100 year period, and we can see that nitrous oxide is 298 times more potent than carbon dioxide. 

The fluorinated gas PFTBA is 7100 times more potent than carbon dioxide.

By Wjfox2005 – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=32658369 

Net Zero Building Tech

A ‘Net Zero’ building can minimize energy and carbon usage as well as generate clean energy using the following technologies:

These include:-

• Roof & wall insulation
• Air filtration and ventilation
• Solar panels
• High-performance windows (including smart glass where appropriate)
• Low flow water fixtures
• Heat pumps
• Energy-efficient appliances & lighting

These can be combined with Passive Cooling or even Passive House methodologies to increase their impact.

How does Smart Glass help Net Zero Buildings?

Smart glass is really a family of materials, much like metal, wood or stone. 

You can read our primer on the basics of smart glass at this link.

Various smart glass technologies can help to achieve Net Zero in buildings, both in energy terms as well as reducing its carbon footprint.

Auto-tinting glass

Auto-tinting smart glass can reduce energy consumption in the building by filtering out solar infrared and light, which reduces air conditioning costs. Examples include electrochromic, dyed liquid crystal and thermochromic smart glass.

Dynamic glass

The dynamic nature of smart glass provides better user comfort, reducing manual (and often inefficient) adjustments in air conditioning controls, with cost implications.

Replacing Motorised Blinds

Smart glass reduces the need for electro-mechanical blinds and shutters on the building facade, which draw substantial electrical power.

Low Reflectance

Smart glass with low-reflectance layers can improve sustainable daylighting by improving light throughput, which reduces the cost of artificial lighting in the building interior.

Transparent Photovoltaics

Transparent photovoltaic smart glass generates clean electricity directly within the window, whilst preserving exterior views. This improves sustainable daylighting, which reduces artificial interior lighting costs (as above).

Clean electricity can also be generated using photovoltaic roof tiles or photovoltaic building cladding. Underlying these technologies we find ultra-low reflectance smart glass which maximizes light throughput to the photovoltaic layer.

These photovoltaic building elements can power some smart glass technologies directly, reducing cabling costs, and reducing power factor fluctuations on the electrical grid.

Smart glass thus contributes to better energy efficiency and a reduced carbon footprint across the global building stock.

Net Zero Buildings Outlook

‘Net Zero’ buildings, viewed in energy or carbon terms, aim to minimize the impact of buildings on the environment

Smart glass technologies can contribute to reduced energy consumption and a reduced carbon footprint by minimizing air conditioning costs and artificial lighting costs.

Smart glass can also be combined with architectural techniques such as insulation, ventilation and heat pumps to bring a cohesive approach to sustainable building design.

If you truly believe that we are facing a climate emergency, now is surely the time to finally bring smart glass into mainstream construction, and no longer treat it as a niche or a ‘nice-to-have’.

Smart glass is a necessity in the same way as smart phones, smart appliances and smart cars.

Unless you really believe that there is a ‘Planet B’ out there somewhere.