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by Sean Hill on Nov 29, 2022
“CO emissions from buildings and construction hits new high” announced the headline from 2022’s Global Status Report for Buildings and Construction. Released at COP27, it paints a gloomy picture of the sectors huge rate of energy consumption and emissions.
Accounting for over 34% of energy demand and approx. 37% of energy and process related CO2 emissions in 2021, the sector is further widening the gap between it and the decarbonisation targets of 2050.
However, amongst this negativity there continues to be pioneering work in eco-friendly architecture and smart low energy homes. Once seen as a quirk of the rich or eccentric, these sustainable, affordable, and forward-thinking properties are springing up throughout the country.
As energy bills continue to rise, and the need to reduce carbon emissions becomes even more critical we look at the growth in popularity of these green friendly and environmentally conscious buildings.
The UK legacy of poor building design
As outlined in a recent Guardian article by Phineas Harper, we have in the UK some of the smallest, oldest, and poorest insulated houses in Europe with more than half built before 1965.
This ageing and inefficient housing stock is the result of mass building predominantly in the industrial revolution which saw small, largely terraced two-up-two down, street facing homes, constructed in narrow streets with poor shading and orientation.
With cooler summers and cheap coal used in open fires, environmental performance and extreme weather were certainly not a consideration!
Deregulation has also led to micro homes springing up, created without planning permission from office blocks and commercial buildings with cramp living spaces prone to overheating with no cross ventilation.
Either too hot in the summer or freezing in the winter, these poorly insulated houses now present a major challenge in the fight against climate change, accounting for 66 million tonnes of emissions in 2019 due to burning coal, gas and oil for space heating and hot water.
As the Building Research Establishment (BRE) states: “The UK has the oldest housing stock in Europe, and most likely in the world. This is largely due to the legacy of dwellings built during the industrial revolution, which still form the backbone of our urban areas today.”
“While still widely valued, these homes present challenges in making them healthy, safe and suitable for the future.”
Whilst new build homes can go some way to offering a solution, the homes which make up most of the country’s stock require retrofit to make them not only habitable, comfortable, and visually appealing for the future, but also to achieve energy efficiency and climate targets.
A zero carbon or low carbon home
When it comes to sustainable architecture and eco homes, there are two main routes to consider, these are zero carbon and low carbon.
Both focus on energy conservation and efficiency through elevated levels of insulation, high performance triple glazed windows, airtight building materials, thermal bridge free construction and mechanical ventilation systems.
The main difference is that in the design of a zero-carbon home the aim is to produce no carbon dioxide through its energy use whereas a low carbon home reduces its emissions to a much more acceptable degree compared to the average property.
What are the design elements of eco homes?
The unveiling of the UK’s first net zero home took place recently in Camden Town.
The UK Green Building Councils Framework awarded the Max Fordham House this accolade in recognition of its emissions as well as its use of natural materials including low carbon cement, timber for the roof, window frames and façade, and wood fibre and cork flooring for internal insulation.
The all-electric home also features a roof-mounted PV to meet 25% of its energy needs with the remaining supplied by a 100% renewable energy tariff.
Much of what it achieved was through the Passivhaus standard of design and construction (or EnerPHit for retrofit). Here the focus is on superb thermal performance, stringent levels of airtightness, minimal thermal bridging, optimisation of passive solar gain, and mechanical ventilation with heat recovery, resulting in homes with a comfortable temperature and minimal energy use, 75% less than a standard home. Heat is generated via sunlight, inhabitants, A+++appliances and LED lighting.
Whilst you may not wish to fully adopt the exacting standards of Passivhaus (or EnerPHit), particularly dependent on your regional climate, home orientation/shape, and whether it’s an existing or listed property, at RISE we will work with you to incorporate a variety of design principles into your new build, refurbishment, or retrofit to create a sustainable home.
- Creating an efficient thermal envelope
Insulation is fundamental to any eco home as it has a major impact on heat gain as well as heat loss, and therefore on energy consumption.
Passivhaus design ensures that through insulation levels any heat lost during winter is negligible and that indoor air and surface temperatures are almost similar, ensuring a comfortable climate.
Exterior walls, basements and attics across all homes can benefit from this approach and use less energy, with high performing, non-toxic and renewable insulation such as sheep’s wool, wood fibre, and hemp used to trap heat and create a thermal envelope.
- Energy efficient glazing
It is unsurprising that one of the biggest culprits of heat loss from the home is glass with a typical home losing 10%. Whilst Passivhaus requires optimised glazing on the south façade of a property with reduced glazing on the north, if you are looking at a retrofit you can make improvements.
The energy efficiency of a window is measured with its U-value, the lower the number the better. Whilst double glazed windows are normally 1.6, triple glazed can sit at an impressive 0.8 with an energy rating of A++, the highest possible rating and recognised by the Passivhaus Institute as the acceptable standard.
With three sheets of glass, and two gaps, triple glazing your windows where possible, can improve insulation, reduce energy bills, and carbon emissions.
Although costly at the outset they will bring with them multiple benefits for your home especially when fitted to the south-facing side.
Additionally, look at passive design techniques to help create external shade and reduce heat transfer from these windows in summer, such as awnings and overhangs as well as trees and landscaping. This will not affect the heat gain from the low sun in winter.
- Renewable Energy Features
Solar energy, heat pumps and biomass boilers are all examples of renewable energy that you can incorporate into the home.
Each allows you to generate your own energy without reliance on traditional sources such as polluting fossil fuels. This then helps to create a carbon positive home in which a building produces more energy than it needs, sending surplus back to the grid.
- Greener Construction
This may apply more to a new build project but is also a consideration where applicable for elements of an energy efficient retrofit. Greener construction includes a number of variables and is not just based upon using recyclable materials.
It is part of what makes a carbon positive home, one which uses sustainable building materials to reduce emissions related to production, transportation, and installation.
Consider where the product was made, how it was made, and how far it had to travel to reach site. If we look at the BedZED village, the UK’s first mixed use sustainable community completed in 2002 they were able to use 52% of their materials from within 35miles.
In addition, look at whether you can use reclaimed materials. The same project used, 3,400 tonnes of reclaimed and recycled material representing 15% of the total. For a domestic project this could comprise any manner of things from doors, tiles, and bricks to bathtubs and light fixtures.
Finally, see where you can make changes by selecting eco-friendly and sustainable alternatives, such as those we touched upon relating to insulation as well as bamboo, cork, straw and hempcrete.
- Airtightness
For a truly eco-friendly and low carbon home airtightness is a major consideration. This represents the fabric first approach to buildings that are less reliant on space heating.
It focuses on the leakage of air from a house, escaping through gaps and cracks in the fabric of the property. In terms of Building Regulations this means that no more than 10 cubic metres of air can escape per hour for every square metre of the envelope surface area.
To put this into perspective a house achieving 5 cubic metres will see their energy use reduce by up to 40%.
Whilst we talked about windows and insulation earlier, it is also important to look at door frames, open fires and chimneys, pipes, and cables.
The use of specific materials for membranes and barriers such as long-lasting flexible mastic is also key. If constructing a new home, then eco-friendly structurally insulated panels (SIPs) made from timber are a positive choice, manufactured off-site they can help to reduce carbon emissions.
- Natural and Mechanical Ventilation
To maintain a healthy and comfortable internal environment in an airtight home, ventilation is a crucial factor.
Airtight properties will often rely on mechanical ventilation with heat recovery (MVHR) systems as well as skylights and natural cross ventilation with windows on each side of the home creating a cross breeze, although the latter is harder in winter and will exacerbate heat loss.
MVHR take moisture from rooms such as bathrooms and kitchens, passing it through heat exchangers which in turn combines it with fresh air coming into the home, releasing this pre-warmed air back into the property.
As it requires ducts to run through the building it must comply with building legislation in terms of installation, design, and inspection, and we can advise you on this.
How an architect will help you achieve your eco home
As you can see whether retrofit, refurbishment or new build there is much to consider when it comes to creating a liveable and comfortable eco home. Here at RISE, we have the experience and skill to help you to achieve your vision.
Our passion in this area has seen continual professional development undertaken across the team with a focus on the EnerPHit standard developed by the Passivhaus Institute. Still a very demanding standard it does relax part of the criteria, recognising the challenges of retrofit projects.
Client led, we look at not only the design and construction of the building, but its eventual end use to ensure that the sustainable house you create is also a home.
If you would like to talk through your project with the team, please do get in touch at mail@risedesignstudio.co.uk or give us a call on 020 3949 8471
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