Welcome back!

I hope you find you’re getting some value for time spent reading my blogs.

In my last, short introductory blog on the topic of ‘Retrofitting our Existing Homes’, I highlighted a number of typical questions that householders have been asking me on this subject. There are so many building types, construction methods, materials, heating and insulation standards that apply to our homes. There is also the financial circumstances and lifestyles that vary from one household to another. But for most existing Irish houses, energy related issues and challenges can be grouped into types that are often quite common. For most situations, suitable technological and retrofit options are available to choose from that are reasonably well tested and proven to perform effectively and continue to be durable over long time spans.

I hope this blog addresses some of these typical issues and offers solutions that are practical and cost effective that should substantially improve the performance of your home. I am steering clear of half-hearted efforts and compromises, often carried out that only tinker at the edges of problems and often need being taken apart and upgraded at a later date. I’m trying to tackle the more fundamental and long-term changes we need to make and to invest wisely in, that minimise the risk of obsolescence or requiring upgrading at a later date.

Before recommending any practical retrofit measures, I would first like to you to explore some of the basic principles of Building Science that may apply to your specific home and to solutions I may recommend for them. So hopefully, with the following guidance, you may understand and appreciate their purpose and ensure that they are designed, applied, installed and operated correctly so as to achieve their fitness for purpose and optimum performance.

There are three fundamental ways of reducing conventional energy use in the home that will save substantially on running costs and that will reduce CO2 emissions at the same time.

By reducing dramatically the energy demands of our home:

This is achieved by tackling all the enclosing elements of the house. This comprises the complete external envelope that separates the heated and temperature-controlled, habitable environment of the house from the very variable exterior ambient climatic conditions,

- Such as protection from cold, wind, rain and snow, or from a combination of all four.  In some circumstances it can include protection from overheating and increasing heat waves.

-This envelope includes the ground floor and all structural elements in contact with the ground, the external walls, roof and attic space and all external doors and windows.

By doing what is described below, you should hopefully achieve a very low energy home compared with the original house.  Say, to reducing the energy running cost and CO2 emissions of a poorly performing house to about one third to even one fifth of what the existing house achieves. It is important to focus first on the energy conservation measures to be addressed, before considering what changes to the heating system or decide what renewable energy system you wish to install to replace a conventional boiler, as described later.

The first and most important area to focus on is your existing home’s standard of performance of thermal insulation and air tightness. Typically, Irish houses are very poorly insulated, draughty with high humidity interiors, relative to standards that can be achieved with construction technology now available. Many energy efficiency technologies available in Ireland today are well tested and proven to perform well over a long durable lifespan. The investment cost of retrofitting is a major factor for householders, where some methods much more affordable than others. However, the cost of upgrading compared to new construction can be a lot more expensive than installing insulation and air tightness, as in state-of-the-art, well designed, Passive Houses or A1 BER rated new homes.

Choosing appropriate products and solutions that are fit-for-purpose and installing them correctly is paramount. Unfortunately, many upgrading projects are designed and carried out defectively.  These often lead to many problems that compromise the upgrading and its investment.

There are constraints arising from existing construction types and interior layouts that can of course limit or compromise possibilities, often where space is required to accommodate high levels of insulation, by applying thick levels of dry lining to interior surfaces of external walls, to concrete ground floors, to roof or existing windows. Heritage buildings particularly have their own intrinsic architectural constraints. These can restrict certain building work options to existing homes, especially when these homes are occupied and people living there when work is being carried out. Also, where external walls are being dry lined, the moving and alterations of existing bathroom fittings, kitchen units, plumbing and electrical services can cause major difficulties and extra costs.

It must therefore be said at the outset that it can be troublesome, disruptive, compromising and expensive to bring our existing homes to a high level of performance, such as to ‘A1’ BER or to ‘Passive house’ standards.

Not withstanding these constraints, major upgrades once completed, will prove to be cost effective and necessary in the long run.  They can go a long way to transforming nearly all our homes into very comfortable, healthy, low-energy running-cost, habitable, comfortable and pleasant, indoor living environments.

Typically, we can bring our average house, BER rated “E” to a ‘B1’ rating in thermal performance of about a third of its existing energy demand. The energy running-cost can be further reduced by switching from oil heating, use of open fires or electric storage heating, to more cost effective renewable energy systems, such as solar, solid log, wood-chip or wood-pellet boilers.  All of this will bring down the high CO2 emissions of our homes and reduce Ireland’s excessive imports of fuel. By doing so, we can future-proof and secure our homes against rising energy prices and future uncertainties of conventional fuel supply.

It can be reasonably practical to be able to transform from a typically ‘E’ rated home to achieve ‘B1’ or even stretch your budget to ‘A3’ performance at a reasonable cost. But getting a poor ‘G ‘rated house up to an ‘A1’ can be extremely difficult and very expensive, but it often can be achieved, as shown on my ‘About the House’ series last year. Heritage, historic period homes and traditional vernacular farmhouses need special and appropriate attention, which I hope to deal with separately in a later blog. These need extra care, so as to be future proofed to ensure their legacy continues to future generations.

The biggest difficulties for most houses built over the last fifty years will be dealing with concrete ground floors or large cold-bridges from masonry, block or mass-concrete walls, especially where they junction with the ground. Also, where internal block work partition walls and party separating walls junction with external walls or dealing with cold bridges around window reveals, jambs, sills and heads, likewise for chimney breasts and stacks. Other common cold-bridge details include junctions of external walls with upper floors or with roof eaves. Energy efficient retrofit solutions that provide effective standards of air tightness, down to say three air changes per hour can be quite difficult to achieve.  The provision of effective and controlled ventilation, to maintain good indoor air-quality also needs special attention, to minimise energy loss. Another critical area is eliminating cold draughts, huge heat-losses from wind infiltration being common to most Irish houses, especially during cold, windy nights.

So huge improvements to our existing homes can be achieved by protecting the complete exterior envelope against all sources of heat-loss, through a combination of extensive energy conservation measures, which I will continue to discuss in next week’s blog.

-Duncan Stewart