NBS | Sustainability: Eco-minimalism: value for money ways of making buildings energy efficient

NBS topic areas

Keep up to date with industry developments

NBS solutions|

Products and services for all construction projects

NBS Building

NBS Building enables you to write concise, technically accurate and up to date specifications for building projects.

ReadMore on NBS Buildings

Eco-minimalism: value for money ways of making buildings energy efficient

Eco-minimalism: the antidote to eco-bling by Howard Liddell, highlights realistic and cost effective approaches to becoming ‘green' and in showcasing ‘eco-minimalism' - a good-housekeeping approach to ecological building design and specification, involving apparently non-glaringly obvious strategies such as insulation, draught-proofing and the use of healthy materials. The book aims to expose the pitfalls of ‘greenwashing' in an immediate, visually-arresting and authoritative way, presenting basic tenets in a quickfire, highly accessible format.

In this exclusive extract from Eco-minimalism: the Antidote to Eco-Bling, we introduce a few basic ways to build in energy efficiency.

Passive solar energy: fewer moving parts to go wrong

Pointing south-facing glazing at the sun and letting it heat up something solid and heat-retaining, like a tiled floor or a brick wall, is a phenomenon that will simply happen sunny-day-in and sunny-day-out, without wear and tear. Unlike an 'active' solar-energy system, passive solar design requires no plumbing or pumps and virtually no maintenance.

It is not magic, and while the 'greenhouse effect' exploited by greenhouses and conservatories means that short-wave radiation goes in and re-radiated long-wave radiation finds it difficult to get out, other forms of heat transfer – conduction (through a material), convection (in the air) and even a degree of radiation (across a space) – all contribute (once the sun has gone down) to a potential for glazing to be a net loser of energy instead of a net winner. Such losses are relatively easy to resolve via shutters or curtains, but this issue does emphasise that with a passive solar strategy the user – not the system – is active, while in an active system the opposite is the case.

Solar shading: essential if a benefit is not to become a real nuisance

Pointing south-facing glazing at the sun is fine for heating a building in the heating season, but such a strategy becomes a liability in the summer. Unless external shading or super-ventilation is included in the design, it is likely that there will be overheating and a resultant cooling requirement – such as air-conditioning.

Post-rationalisation of past designs often seeks to ascribe to a ubiquitous 'modern'-materials palette virtues that might not stand up to scientific scrutiny. Unfortunately, once the sun is through the glass it contributes to the building's greenhouse effect. Internal blinds merely prevent glare and visual discomfort – they do nothing to mitigate heat build-up. Therefore, it is essential that a summer cooling strategy includes external shading – for example through external blinds or brise-soleil.

Solar shading, in the form of brise-soleil, is often applied as mere decoration, adding interest to an otherwise unpromising façade without doing the job it is designed to perform. Such devices feature occasionally even on north elevations, where – certainly in the UK – their contribution to indoor climate control is zero.

Low-energy equipment: start by demanding less energy

When the Chinese government decided in the late 1970s to supply its whole population with fridges, its less energy-efficient choice of model – made on a marginal capital-cost-saving basis – resulted in the electricity-supply industry having to build a significant number of additional power stations to cope with the extra load. The choice appears especially strange when one considers the lack of a free market at that time. The option was there to buy a 'job lot' of a specification to the benefit not just of the state but of all comrades.

Energy rating is one of the few areas in which the EU has successfully implemented an energy-labelling and savings strategy. As this publication goes to print, the UK government has finally decided that phasing out highenergy-use light bulbs will not result in the collapse of the consumerist economy – and might even help it. In the meantime, it virtually always makes cost-in-use sense to buy energy-efficient appliances, and while clockwork radios and torches may seem oddball, they never require a trip to the shops for spare batteries – merely a modicum of human exercise.

Phantom loads: there are numerous, unnecessary, 'phantom' loads making demands on the electricity supply system

The introduction of low-energy equipment and dealing effectively with inefficient standby modes can be achieved without threatening personal or corporate standards of living. All that's lacking is the political will to phase in the 'one-watt standby'. Around 10 per cent of the national electricity grid and 1 per cent of the nation's total energy demand is accounted for by the standby buttons on our electrical and electronic equipment. What is remarkable is that one-watt standby is achievable with currently available technology. Indeed, there is a whole movement seeking to promote such a shift.

What is even more significant is that, as with digital television, it could easily be phased in over a very short period as people replaced their equipment. One-watt standby could certainly be achieved in less time than it takes to construct the nuclear power station required to cope with the utterly unnecessary waste caused by inaction on this possibility.

In Australia in 2005, an announcement was made of a strategy for the implementation of a 'One Watt' standby target for appliances, with the potential to save the average household up to AUS$100 per annum and significantly reduce greenhouse-gas emissions. Given that this is an obvious 'win-win' solution, it seems very odd that a strategy to implement such a switch to low-energy standby electronic apparatus is taking so long to introduce to the UK. Because of not having to construct more generating capacity, there is a reduction in the expense of running additional power to the benefit of all.

Renewable tariffs: defraying the carbon cost of essential electricity

It is common for clients wishing to 'go green' to look to a domestic-scale solution rather than connecting to a networked system. In generating their own energy, they take both the capital expenditure and the ongoing maintenance on board. However, each case needs to be taken on its merit. For example, a house-mounted wind turbine is likely, in most locations, to be considerably more expensive per watt generated than a larger, more appropriately sited wind turbine. It will also generate less output per money or carbon unit invested. It will therefore probably have a larger environmental footprint than connection to a network that is exploiting wind where the wind blows rather than in a more sheltered, built-up area.

Every site is different and has its own most appropriate renewable energy source. However, very few plots are capable of efficiently sourcing their own total energy requirement either on-site or close to it. In this circumstance, the option is open either to look to a more appropriate technology or to buy into a renewables tariff from a supplier who already has a lowcarbon grid supply network. A recent client, when informed that a city-centre site was poor for exploiting wind energy, elected to buy into a turbine 100 miles away. Such a direct link was considered necessary within their carbon-neutral marketing strategy.

Minimum boilers: there is an unmet need for low-output boilers for low energy housing

Until recently, domestic boiler installations have been oversized for use in energy-efficient houses, and therefore have been working inefficiently. Given that boilers work most efficiently when operating at full load and inefficiently when on reduced load, there is a clear wastage in both the additional cost of the redundant installed capacity and the economic operation of such systems. It has only recently become possible to obtain high-ratio turn-down boilers (up to 4:1 turn-down), which arrangement allows them to work efficiently at both high output (say, 16 kW) and low output (say, 4 kW).

With the advent of ever-increasing numbers of energy-efficient homes, the further development of purely low-output condensing boilers is to be welcomed.

Passive House Standard: There is no such thing as a zero energy building, but there can be a zero-spaceheating building

The 'passive house standard' is defined as a standard of dwelling that not only does not require any heating system but also cools down by no more than half a degree Celsius over 12 hours. This might seem quite stringent, but such houses have been built in central Europe, Scandinavia and Canada for years.

There is a debate about the extent of the (electricity) demand required by the heat-recovery systems that are usually specified in order to avoid heat loss in the extract ventilation air. However, this is an 'advanced-class' discussion in the context of the poor insulation and airtightness standards currently prevalent in buildings being constructed the UK.

New clients very rarely approach our architect's practice asking for a passive house; it is, however, very common for them to have a strong opinion about supply-side technology – be that a heat pump, a wind turbine, a solar collector or a biomass boiler. The possibility that none of these might be necessary in the first place is currently not even part of the public debate.

Extract from Eco-minimalism: the Antidote to Eco-Bling by Howard Liddell.

To order a copy of this book, please visit RIBA Bookshops.