In November 2021, eyes across the world turned towards Glasgow and the COP26 summit as world leaders negotiated international strategies to limit the effects of climate change. The Glasgow Climate Pact signed at the summit’s conclusion promises to “keep 1.5C alive” and “phase down” global reliance on coal power, but the consensus on its success is decidedly mixed.

As it stands, “the world is currently not on track to limit global warming to 1.5 degrees” - the goal agreed at the COP21 Paris Agreement in 2015. Projections based on current data predict a temperature increase of 2.4 degrees by 2030, a figure with disastrous implications for global weather systems and climate conditions in many countries. 

The summit covered a wide range of key considerations for countries and public sectors pledged to lower carbon emissions. You can find useful links to the negotiations, goals and resources at the bottom of this article. We focus on what 'net zero' really means for homeowners and builders. 

What’s the impact of construction on climate change?

Thursday November 11th saw the focus on Construction, Cities and the Built Environment. Buildings - their construction, operation and heating - account for a hefty 39% of global carbon emissions, and the urban environment is only predicted to grow in the coming decades.

Source: Global Alliance for Buildings & Construction, 2018 Global Status Report: IEA

48% of emissions from buildings are generated from energy usage in existing homes - predominantly via fossil fuel boilers. 62% of energy usage emissions are produced by heating. (UKGBC). Roughly half the homes in the UK have uninsulated walls.

It will be impossible to meet the UK’s 2050 Net Zero target without significant disruption to the way we build and heat our homes. Ambitious? Yes - but in the last 30 years British governments have grown the economy by 78% while reducing emissions by 44% (Source: Climate Change Committee). That shows green growth is real.

What is a Net Zero building?  

Net zero, in general, means that we produce less carbon than we remove from the atmosphere.
The UK Green Building Council divides a ‘net zero’ building into two distinct definitions: construction energy - carbon linked to the construction materials (“embodied carbon”), equipment and processes involved in development - and operational energy, the daily emissions generated by lighting, heating, and, broadly, simply using the building stock.

What's the goal of Net Zero? That carbon emissions associated with (a) construction stages up to practical completion and (b) functional energy use on an annual basis are zero or negative. This is achieved by using offsets, on-site or off-site renewable energy and designing highly energy efficient buildings from the building fabric to the heating systems, glazing and airtightness.

So you want a thermally efficient, low carbon home. What's involved? 

In new builds, the most effective way to achieve this is though energy efficient design. Existing dwellings should be upgraded in thermal performance through retrofitting, insulation and design alterations. Here are some suggestions to lower your home's carbon emissions for the long term. 

Build to a low-energy standard and specification. The Future Homes Standard is expected to alter the current UK building regulations to reduce carbon by 70-80% in new homes by 2030. Passive House (for new builds), EnerPHit and Energiesprong (for retrofits) offer clear, road-mapped ways to design, build and refurbish homes to low-carbon standards and significantly reduce the operational energy of homes. You can work with consultants from the Passive Institute to ensure the building meets its stringent performance requirements.  

Monitor and limit energy usage in your home. The Government plans to expand the use of Smart metres (SMETERS) that allow you to modify the temperature settings of your home. Improving insulation in floors, roofs and other easy-to-access areas are available to many homeowners.  
You can expect greater emphasis on measuring the in-use performance of all homes in the coming years. 

Upgrade your heating system.  Replacing the heating system of existing houses is key to reducing operational energy of the UK’s housing stock. Gas boilers, which currently heat 85% of UK homes, will be outmoded by 2025 in favour of heat pumps, considered the most energy efficient low carbon heat source.

Consider retrofitting to avoid embodied carbon from new builds. Retrofitting existing homes to be more energy efficient extends their lifespan and avoids the significant uplift in embodied carbon created in replacing old buildings with new. Embodied carbon refers to the CO2 created in producing materials. It includes transportation, extraction and production of materials and is responsible for roughly one third of carbon from the built environment. Embodied carbon can be mitigated by wider emphasis on reusing building materials and structures rather than rebuilding from scratch.

Work with landlords towards mutually beneficial green leases. Make public commitments to only taking ‘green leases’ or occupying low carbon spaces (considerations might include being fossil fuel-free, provision of 100% additional renewable energy, waste reduction or management, water efficiency etc.). Both owners and occupiers can take responsibility for the sustainable operation and occupation of a property. UKGBC envisions that by 2025 only green leases will be accepted.

“To keep the temperature of the planet under control – limiting its increase to 1.5 degrees - the science dictates that by the second half of the century, we should be producing less carbon than we take out of the atmosphere. This is what reaching ‘net zero’ means.” 
- Alok Sharma, COP President-Designate

What impact does triple glazing have on your home's energy efficiency?  

Windows are responsible for 20-25% of heat loss in most homes. Yours will make a significant difference on your heating bills and carbon emissions – and your comfort level on a daily basis.  

So what can you look for in an energy efficient window?  

Ideally, specify thermally efficient triple glazing.  Avoid metal frames in favour of timber, a much better insulating material. Alu-clad timber-framed windows combine the thermal efficiency of wood with the weather protection capacity of powder-coated aluminium for the best of both worlds.  

Be conscious of the U-values of your glazing. Aim for at least <1.4 W/m2K whole window U-values for double glazing and <0.85 W/m2K for triple glazing. Our range of double and triple glazed windows easily meets these standards. With U-values as low as 0.67 W/m2K and multiple products suitable for Passive House building as standard, they reflect our commitment to energy efficient building. 

Consider airtightness. Look for multi-point locking mechanism with at least one robust seal (or gasket). Our windows have espagnolettes with multiple locking points in both windows and doors and dual seals. These also make for a more secure window.  

Our double and triple-glazed windows are designed and engineered to deliver incredible thermal performance, providing durable materials that will enhance your home’s performance and lower carbon emissions for decades.  

Useful Links & Resources

COP 26 - what is it? 
COP stands for Conference of the Parties. It is an annual conference between signatories of the United Nations Framework Convention on Climate Change (UNFCCC) - 196 countries and the EU. Read the full programme and learn more here

Net Zero Pledges by Country
Click here for a helpful guide to the climate pledges of each country, evaluated according to plans, policy level and coverage.

The Road to Net Zero in the Build Environment
Read the UKGBC’s detailed overview of the Road to Net Zero for the built environment. They have developed suggested action plans for stakeholders - developers, occupiers, architects and more. 

A Net Zero Toolkit
Click here for an easy-to-understand toolkit to work towards Net Zero, for building professionals and homeowners. 

Frequently Asked Questions

What is net zero ?

Net zero, in general, means that we produce less carbon than we remove from the atmosphere, cutting greenhouse gas emissions to as close to zero as possible so that any remaining emissions can be offset and re-absorbed by forests, oceans and other natural carbon sinks.

What is the global net zero target ?

To prevent the worst impacts of climate change, global temperature increase needs to be limited to 1.5°C above pre-industrial levels. To do this, emissions need to be reduced by 45% by 2030 and reach net zero by 2050. By 2050, “we should be producing less carbon than we take out of the atmosphere.” (Alok Sharma).

What are net zero buildings ?

Net Zero buildings’ carbon emissions - all carbon associated with construction materials (“embodied carbon”), construction and operational energy use on an annual basis - are zero or negative. This is achieved by designing highly energy efficient buildings, using on or off-site renewable energy and offsetting any remaining carbon.

Net zero vs passivhaus

Net zero homes must produce as much energy as they use in a year using renewable energy and carbon offsets, while Passive Houses’ heating demand must not exceed 15kWh/m2 annually. This is achieved by meeting more stringent design and construction requirements than Net Zero’s.

Are net zero homes worth it ?

Net zero homes are key in the global goal of net zero. Owning or building one can save you operating costs of up to 80% compared to existing homes. However, Net Zero homes are more expensive to build, requiring expensive systems that may be offset only after many years of operation.

Are net zero and carbon neutral the same ?

Both net zero and carbon neutral share the ideology of cutting greenhouse gas emissions. ‘Carbon neutral’ tends to be associated with business targets or individual products and refers to net zero CO2. Net zero targets a larger scale - it means neutralising all greenhouse gas emissions, not simply CO2, globally.
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