Improvements in energy efficiency in buildings since 2000

This post is largely based on the article Advances Toward a Net-Zero Global Building Sector in Annual Review of Environment and Resources 2020 [1]. The article is open access so anyone can read it for free. It explores why energy efficiency is important for net zero emissions and charts improvements since 2000 in different regions of the world. It briefly compares the Passivhaus standard with other standards widely used for low energy buildings. The focus is on the UK although much of the evidence comes from elsewhere, primarily Europe.


Energy efficiency is critical but health must be protected.
Energy efficiency is critical on the path to net zero emissions because our current needs are considerable and replacing current building energy use with new renewable generating capacity (not using gas), energy storage and transmission capacity would be even more expensive. Efficiency is also beneficial in other ways including improving health and reduction of energy poverty. For example, in the past efficiency measures have contributed to sick building syndrome – to avoid this, air tightness must be accompanied by adequate ventilation. Also temperatures below 18°C can trigger health problems in vulnerable adults directly; there is evidence that 18°C is warm enough for most people [2].


Stringent energy efficiency standards make homes cheap to heat.
The PassivHaus energy standards are widely used for social housing as they reduce the energy bills for tenants. Lower bills and healthier tenants reduce costs for landlords too as tenants are less likely to fall into arrears with the rent [3].


Passivhaus standards for new build are achievable in all regions of the world.

There are many examples of Passivhaus certified buildings in the northern hemisphere where winters are cold but relatively few in the south where the main requirement is cooling[1]. The requirement for Passivhaus certification on a new build is that total heating and cooling energy demand should be no more than 15 kWh/m2/year (1350 kWh/year for a typical home with 90m2 floor area).  For retrofit the requirement is less stringent, at 25 kWh/m2/year (2250 kWh/year). This is still huge reduction on typical UK homes where energy demand is typically 11,500 kWh/year for gas alone, ignoring electricity (according to British Gas). 

Air conditioning will be more widespread by 2050.

Very few homes are cooleded with air conditioning, at the moment. However, climate change will make cooling more essential by 2050 [4]. Passivhaus standards are a challenge in hot humid regions. In regions where the main requirement is for cooling, even very efficient buildings can use 90-180 kWh/m2/year for cooling compared to 15 kWh/m2/year for heating. The heating requirement can be reduced by super insulation and ventilation with heat recovery (MVHR). Cooling that does not increase energy demand is best achieved by shading (such as deep eaves over windows) and stack effect natural ventilation. Sadly these are hard to retrofit. Also dehumidification may be needed as cooling humid air can lead to condensation which allows mould to grow.

Energy Efficiency in buildings has improved substantially since 2000 as shown by Figure 2 from [1].

Figure 2 from [1] showing decreasing energy use intensity for home energy since 2000.

However, much of this improvement has been offset by increasing building size, especially outside Europe.

The best time to install energy efficiency is at build time or when maintenance is required.;

Retrofitting energy efficiency measures into existing buildings is often very expensive as well as a major hassle for residents. In comparison, the marginal cost for efficient components such as windows are often quite small in comparison to the anyway cost of replacement.

Energy efficiency retrofits can easily take 10-20 years for payback in lower bills and this is too long for most home owners or landlords. Hence financing packages are needed. Also these retrofits are a major hassle, requiring planning permission and contractors to be hired and managed. During the retrofit, parts of the building may be unusable or at least need to be emptied of furniture. Temporary accommodation may be needed. (We conducted our retrofit in phases, with each phase requiring some furniture moved into storage but we never moved out. This was possible because we live in a large home that is arguably under-utilised.)

One stop shops such as Action on Energy Cambridgeshire can reduce the hassle and facilitate access to funding schemes.

One stop shops can reduce the hassle, providing planning advice, project management and often access to finance. We used an architect for project management but there are also specialist firms such as Ecofurb. Some local councils offer a one-stop-shop service through a partner. Cambridgeshire uses Action on Energy

References

[1]  Diana Ürge-Vorsatz, Radhika Khosla, Rob Bernhardt, Yi Chieh Chan, David Vérez, Shan Hu, and Luisa F. Cabeza, (2020) Advances toward a Net-Zero Global Building Sector, Annual Review of Environment and Resources 

[2] (R. Wookey, Dr. A. Bone, C. Carmichael, A. Crossley, 2014) Minimum home temperature thresholds for health in winter – A systematic literature review (Public Health England) online. 

[3] Sustainable Homes (2016) Touching The Voids: The impact of energy efficiency on social landlord income and business plans (2016), online 

[4] J. Crawley, S. Ogunrin, S. Taneja, I. Vorushlyo and X. Wang, Domestic air conditioning in 2050 (UKERC, 2020) 

[5] EnerPHit: The Passive House Standard for retrofits

The Environmental Cost of AI

With the UK Government's recent announcement about investing heavily in AI, it's appropriate to ask: what is the environmental footprint of all the computing infrastructure that this AI requires?

The answer is simple: it's massive. While there are huge uncertainties, some of the projections have the AI boom causing data centres to generate more carbon emissions than Africa and South America combined. 

The recently announced plans for AI expansion lead to huge increases in resource requirements, and on relatively short timescales. The power needed by AI might exceed that used in all the world's current data centres within 3 years.

That's going to need a lot more electricity, which is likely to increase carbon emissions in the short term, before renewable generation ramps up – and that’s not to mention the carbon footprint of putting up such massive buildings to house the servers and manufacturing the servers that go into them. 

For the longer term, some of the tech giants are starting to look at small modular reactors (SMR, i.e. small nuclear reactors) to power their data centres. Microsoft is trying to bring one of the reactors at Three Mile Island back online. Even if you can generate the electricity, generally there isn't enough grid capacity to get it to the right place, which is one reason why there's such interest in putting the generator, such as an SMR, right next to a data centre.

It's not just drawing electrical power that's a problem. Gargantuan amounts of water, already a scarce resource, are needed for cooling, as all this electricity gets converted into heat.

All this environmental damage leaves open another question: will the benefits from AI outweigh the environmental damage it causes?

For a good overview of the issues about AI and sustainability, this report from the Green Web Foundation is a good read, and this article from UNEP closes with five recommendations to “rein in the environmental fallout of AI”. A great book on the topic is the “Atlas of AI: Power, Politics, and the Planetary Costs of Artificial Intelligence” by Kate Crawford.

To find out how to turn off AI in your search engine or on your device, just search the phrase “how to turn off AI on…” and instructions often come up.

Blog post by Peter Tribble. Peter also has a personal website: https://ptribble.blogspot.com/

Improving your web experience - and saving carbon emissions

We spend a lot of our time browsing the web, but have we thought of the carbon emissions involved in getting a web page to be shown on our screen?

There's a long chain involved. The web page has to be stored on a server, potentially processed for consumption, sent out across the network, being passed through multiple devices on its path to you, before finally being processed by your own device so as to look just right for you to read it.

Fortunately, much of the work involved in calculating the environmental impact of the web has been done for you. Sites such as Website Carbon and Ecograder can estimate the carbon emissions due to viewing a web page. This takes a range of factors into account, from storage and processing of the page, transmitting it across the network, but also whether the server is powered by electricity from renewables or fossil fuels.

Review of 2024

How was 2024 for you? Do you even remember? Reviewing our achievements helps to give us a boost for the year to come. So here is a boost for all our members, and an enticement for anyone considering joining in, of how much fun we have..

This is mostly based on the report for the AGM in October, including some highlights that appeal to me. You can look at the slides in full here.

Repair Café (partners with Cambridge Carbon Footprint).

The Repair Café project, which is a partnership with Cambridge Carbon Footprint (CCF), now has more than 40 groups in Cambridgeshire so there are several repair cafes a month depending on how far you are prepared to travel (see events coming up). This year on International Repair Day (19th October) there was one in partnership with the Grand Arcade and there were also ones in Cottenham and in Haddenham on the same day. Of the three we had the highest rate of successful repairs, though admittedly not by much. The picture below was taken before the end. Our final figures were 40 items and 73% repaired.

Picture credit to Sandy and CCF

These events would not happen without the repairer volunteers and this year we are especially grateful to the team from Sentec who have proved keen supporters. Also during the year we signed the Repair and Reuse Declaration calling for more support for the circular economy including making repair more affordable, expanding regulations to cover more consumer goods and setting repairability standards.

Empty Common Community Garden and the Resilience Garden

Empty Common Community Garden continues to thrive, and the hut is ever more popular as a venue – sometimes for cover for a rainy day – sometimes for a party.

This year we launched the Permaculture Trail on the website, linking a virtual tour of the garden with permaculture principles. 

Charlotte who runs the ECCG is also in charge of the Garden of Resilience by the Guildhall - another demonstration of permaculture.

Water usage survey

What do you do to save water? In recent years we have seen our chalk streams suffering due to lack of water because we take too much for our taps. Also, we use a lot of water for hygiene, perhaps more than we need. This year we ran a survey, asking some quite intimate questions. Read the results here.

Water Sensitive Cambridge

Also on a water theme, we were partners with Water Sensitive Cambridge, which was seeded by Transition Cambridge and is now a CIC. Their aims are to make places for water and nature, and change how we think about and treat water. They made their first on-street rain garden this spring in East Chesterton and it proved itself in a downpour soon after, with reduced flooding that dissipated quickly - as we reported on this blog.

Reduced flooding and rapid dissipation of the rainwater after a storm

See more pictures and videos on their website.

Films

We showed four films this year at Storey's Field Community Centre, all on an environmental theme and well attended. Each film was followed by a discussion with the audience and in most cases with input from members of the team that made the film. In February we showed Pure Clean Water which is about Hobson's Brook and how our overuse of the chalk aquifer has affected it - and what can be done. This showing was the inspiration for the water use survey. In the Autumn we ran a season of three films: Six Inches of Soil, Once you know, and Fugolburna. We'd like to do more so let us know if you have ideas for films to show.

Other groups and partnerships

Other projects continue to thrive such as:

• Energy Group – this year’s topics included DIY energy saving, air quality and inter-seasonal storage
• A Toys Life and Beyond - swapping childrens’ toys and learning about the circular economy while supporting young families.
• The Environmental Discussion and Reading Group 

Also we are delighted when groups we have spawned continue to grow. The Resilience Web is now a CIC and has directories for eight distinct nexuses of community groups including Cambridge (3 webs), Bath, York, Durham, Norwich and South West London. The new "A Penny Saved" web highlights groups in Cambridge that help save money alongside their environmental or social justice aims.

We hope some of these things will inspire you to take action on climate change. Perhaps you will get involved in one or more of our groups, or perhaps you will browse our website for advice such as the Permaculture Trail or the Energy Group Advice pages. The important thing is to take some action. We are making progress on climate change but not fast enough.

How to use the Christmas break?

Many of us get a week or so off over Christmas (whether we celebrate Christmas or not). For two days there are no shops open, though there is always online shopping and social media to keep us amused. But don’t you think the winter break should be special?

Special means different. Different can mean different things but it needs to involve a change of pace and a change of focus. I like to take a walk and see what I can see, or meet up with friends and have a natter with no distracting mobiles. The important thing is to slow down and look outside of yourself – at people you (think you) know well, or complete strangers, or just the world. The main thing is to look and to listen.

 

I am no photographer but here are some pictures I have taken on my walks around Cambridge at Christmas time.

 

This picture was taken on Christmas Day last year. The saddle cover must be 9 years old because the pantomime is dated 2014.

 

Frosted spider web, woven on temporary fencing by Jesus Lock, which was under maintenance.

An attic window which has frozen up on the outside. These frost patterns seem to be increasingly rare, presumably due to climate warming.

 

Not Christmas Day - Feb. 2024- but it's a lovely picture anyway. Floods are getting more common but it is still possible to have fun like this little boy (click on the picture for a larger version).

Transition Cambridge likes to celebrate the new year with a gentle walk. Next year we will meet by the Green Dragon bridge. All welcome, old friends and new.

Transition Cambridge New Year's meander last year (or was it the year before?) From the Chisholm Trail, near the football ground. From the left, Ben, Liz, Anna, Sam, me (Nicola), Charlotte, Tamsin, Rory and Jacky.

Making Halloween and Christmas fun *and* sustainable

I saw a ghostly crisp packet in the road last night – it seemed to be positively luminous but it was just reflecting the street lights. This, plus a black dog in evil demon costume, reminded me we are fast approaching Halloween, which is a great opportunity for harmless fun. Ghoulish costumes to startle passers-by, sweets to enjoy, maybe some ancient magic spells …

Photo by Beth Teutschmann on Unsplash

However, like the plastic crisp packet, Halloween and Christmas can be very wasteful - if we are not careful. Cheap (plastic) spooky costumes that we wear once and then throw away and sweet wrappers that do not get recycled – these are the main sources of extra waste at Halloween. WRAP has much to say about this.

Here are some easy ways to reduce waste at Halloween and Christmas:

Making a rain garden

This new little garden is flooded after the storm - but no worries because it is a rain garden and this is meant to happen. The idea is to take water off the road - hence the kerb cuts to allow water to flow into the three new sunken gardens along the grass verge. Fallowfield has poor drainage and floods regularly after heavy rain, but this time there was much less flooding than usual and it dissipated more quickly. The plants need to tolerate both floods and droughts, as that is the weather we get these days.

After the rain, Fallowfield rain garden number 1