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Sustainability in Older Buildings.

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Improving the Insulation on Older/Poorly-Built Buildings.

AKA Raising the B.E.R. on (older) buildings.

The B.E.R. Rating. Building Energy Regulations of a building means to improve it’s insulation and ultimately to lower its eco-footprint and cost in terms of fuel-consumption. It’s a frightening thought that buildings bought before the UK building boom of the ‘80’s (Ireland of the late 90’s) now cost more to heat per year than the initial cost of the building itself. Fuel prices have risen at 1.5 times the rate of inflation over the last 30 years.

It is generally accepted (B.E.R. standards, LEED (US), SAEI- Ireland, Department of Energy and Climate Change (DECC); UK) that 35% of heat is lost from a building via poorly insulated walls.

Heat is lost in ALL directions.

Heat is lost in ALL directions.

The overall heat loss from a building can be calculated as

H = Ht + Hv + Hi   where H = overall heat loss (W)

Ht = heat loss due to transmission through walls, windows, doors, floors and more (W)

Hv = heat loss caused by ventilation (W)

Hi = heat loss caused by infiltration (W).

Heat-loss in buildings (or heat0gain in warm lands demands the value of the building every generation or less nowadays. (Protek-usa. Heat-Gain-Loss-Buildings.pdf). this pdf starts with a very good definition of heat loss via radiation, conduction and convection.

N.B. Sand-cement render on the exterior of a building (especially if insulating the interior) will result in the building ‘sweating’ and possibly developing Merulius lacrimans – dry rot – or -Serpula lacrimans – ‘Real-Dry-Rot’). Both will destroy a building and even its neighbours. If a house is to be ‘sealed’ great care must be taken that it remains “breathable”.

There are two (generally) accepted ways of insulating a building (insulating the envelope);

External; “Bubble-wrapping” the exterior – e.g. polystyrene slabs fixed to the exterior walls (using plastic ‘mushroom’ plugs) and plastering with a patent-polybond-skim over a mesh that holds all in place. This technique ‘defaces’ the exteriors and ‘technically’ needs planning permission.

Cross-section of external insulation.

Cross-section of external insulation.

Internal; fitting patent pre-insulated slabbing to interior walls (ceilings too if possible) to retain the heat generated within the building. Fixed as above or with laths between wall and slab this system is usually seen as the best as it retains heat before it hits the exterior wall and is absorbed (before being lost if there’s no external insulation). This system is often eschewed as it reduces the volume of the room (room-size) considerably in small homes/offices. It is seen as the most desirous in larger buildings as the heat is retained and in fact rather like any light-weight structure (boat-caravan) is easily heated very quickly.

In both cases however the incidence of leakage (drafts) and of course doors, window, and especially glazing must be considered. Poor glazing techniques (ie single-glazing or poorly designed/compromised/faulty) can cost 23% heat loss normally but even far more if the rest of the structure is well insulated.

From ; “Internal insulation systems involve using insulated dry-lining boards. These boards comprise of 12.5mm of plasterboard with insulation bonded to the back with a vapour barrier between the two. The insulation ranges in thickness from about 25mm to approximately 60mm though this depends on the make and availability. A lot of these boards would have similar levels of thermal conductivity because the main types of materials that are used, i.e. polyurethane and polyisocyanurate, have very similar thermal properties. However, it has the disadvantage of placing the thermal mass of the wall outside your heating envelope. External insulation is another option, which would have the added advantage of keeping the thermal mass of the concrete walls within your envelope. It is very popular method in Europe, and is becoming more common in Ireland. With external insulation, the insulation panels are applied to the walls, then a protective mesh that protects the insulation against impact damage is applied, then a basecoat and usually two coats of render”.

Floors are often disregarded as it’s generally thought that heat rises – which is true. But as temperature rises within a structure the heat will always seek to find a way out; even downwards. Floor insulation must reflect what is planned above. 15% heat loss is the accepted figure but again as the better insulation of the upper areas improves the rate of loss through the floor will increase.

Air Seal

A gap of just 1/8 of an inch under a 36-inch door lets in as much air as having a 2.4 inch wide hole in the wall. Since people often adjust the thermostat and leave heat running longer when they feel a draft, preventing air infiltration can greatly reduce energy usage. See ‘Notes’ below.

Air-pressure-tests and infra-red video cameras

will show leaks and vents as well as ‘cool-spots’ in covered areas that are lacking insulation.

Detailed business information on Air Pressure Testing Companies located in the UK, including photos, contact details and customer reviews.

Heat-Exchange Systems. aka Heat Recovery System.

No discussion on heating/cooling any building can Not but consider ‘heat-exchange-system’ see; Heat-Exchange Systems.




‘Geo-thermal’ means absorbing some of the latent heat from the earth (or running water/large body of water) and enhancing the heat by passing it through a heat-exchanger – the inverse of a milk pasteurising system. It’s usually used for underfloor systems (at about 33ºC) though new radiators are coming on the market to work with low-heat-radiators.

Geothermal-Heating-Systems simple


I opened a website on heating on old home and one thing jumped out at me – I hadn’t mentioned the last time – THE most obvious and the FIRST thing ones does – AUDIT. If it ain’t measured it won’t count (or get done).

It’s the most important thing to do – with any structure. Don’t waste money/time until you know where the leaks are. An ait-test and infra-red camera wre the best way to see where the warm air is leaking and where the insulation is needed. Before and AFTER remedial work; More information on blower door tests>>
See; Improve Your Home’s Energy Efficiency – Start With an Energy Audit!
  • Search for articles on old house websites such as the Old House JournalExit EPA Disclaimer
  • Reference books such as Greening Steam: How to Bring 19th Century Heating Systems in the 21st Century (and save lots of green!) by Dan Holohan
  • Ask a question online at
Get this article – very American but less chance that your lecturer will have seen it, excellent resource;  
It’s really difficult to super-seal an older structure though with stone there’s a better chance than wooden/timber-framed however there are a large number of green features and design principles are simply impossible to incorporate in any building after the fact. 
Scotland – links and news; Scotland.national-retrofit-programme 
Heat requirements for the building; Can I fit underfloor heating in an old house?
‘A major factor with UFH in a renovation project is the heat requirements for the building. A system will have a specific max. output, dependent on floor type, and if insulation is limited – e.g. if you have period single glazing and solid walls – it will be difficult to get comfortable room temperatures in very cold weather. Any company you work with must carry out a full heat-loss calculation room by room. It’s also best to have a temperature controller for every room.
‘The two main floor types in old buildings are screeded and timber-suspended. The screeded floor will give a higher heat output, but you will have more difficulties installing UFH, because you will have to dig out the original floors – or lose a lot of headroom putting down a new floor on the original. A timber-suspended floor will accept UFH onto your original joists and give a floor lift of about 1.5cm and so, in many ways, offers an easier option.’ However the insulation must be ‘top-notch- foil-backed etc to ensure heat doesn’t take the easy option of ‘heading South’ – literally. Heat will ALWAYS go to the cold(er) areas.
UK ‘Green Deal’ offers ideas, grants and actual help; Once again they start by demanding one gets an AUDIT first. If it ain’t measures it can’t be counted!! However there are pitfalls to be negotiated; See Gardian article;
Whilst double glazing and carpets are a good start, draught proofing and insulation of suspended floors will be a benefit and for solid floors, the addition of thick underlay and/or insulation. Internal or external solid wall insulation are required to make flats really low energy and will make them really cosy and eliminate many of the condensation and mould issues associated with cold walls, but this should be considered as part of a comprehensive low energy strategy, that in-cavity wall insulation can lead to damp issues in rare cases. For example, the insulation could offer a path for wind driven rain if the external wall is highly porous, poorly pointed or cracked, or the building is extremely exposed. This risk may be reduced if bead insulation is used instead of fibre, but there isn’t much research on this. Breathability is essential !!
In buildings where part of the wall is solid, for example in ring beam construction, the warmer insulated walls may accentuate condensation at the corner of the wall with the floors and ceilings. Finally, the insulation may reveal building faults such as blocked weep holes or missing cavity trays.cludes heating, ventilation, lighting, appliances and renewable systems.The most cost effective way of minimising draughts from a disused chimney is to use a chimney ballon. 1010global./energy-saving-old-homes;
Doing a bit is better than doing nothing – wearing a hat and no gloves is much better than no hat & gloves.
Schools, UK;  Here, Robert De Jong, LessEn programme manager at the ULI, explains the findings, outlines how Dorset topped the table through its sustainable property team and provides schools with tips on how to become more energy efficient.
Climate debate
A basic misunderstanding skews the entire climate debate. Experts on both sides claim that protecting Earth’s climate will force a trade-off between the environment and the economy. According to these experts, burning less fossil fuel to slow or prevent global warming will increase the cost of meeting society’s needs for energy services, which include everything from speedy transportation to hot showers. Environmentalists say the cost would be modestly higher but worth it; skeptics, including top U.S. government officials, warn that the extra expense would be prohibitive. Yet both sides are wrong. If properly done, climate protection would actually reduce costs, not raise them. Using energy more efficiently offers an economic bonanza–not because of the benefits of stopping global warming but because saving fossil fuel is a lot cheaper than buying it.

Passive-Solar Heating. (aka the No-Brainer).

What is a Passive House? It is a building in which a comfortable interior climate can be maintained without active heating and cooling systems. The house heats and cools itself, hence “passive”. By good design and an average 10% ‘extra-spend’ in design and building will eventually save many 10’s of thousands of Euro or Pounds in fossil-fuel heating-bills (and airconditioning). See;

However as we are discussing older buildings we must assume that other than physically turning a building on its axis to avail of ‘solar-gain’ and to build (sympathetically) around it possibly with a forest to cut-down on chill-factor to NW, N, NE. We must concentrate on apertures, walls, roof and flooring. Further measures – keeping the heating-bills down by reducing the temperature by a degree or two can be found in this pdf;

A book issued hand-in-hand with the Anglican Church offers help; Creed and Creation: A simple guidebook for running a greener church. 2007.

Flooring: When insulating the floor is it possible to add underfloor heating? Underfloor heating uses water heated to 33ºC as opposed to ‘normal’ heating (radiators) which runs at 65ºC.

Notes on insulation and ‘off-grid’ homes;

Australia; A push has been made to help homeowners in providing their own power.

In France A push has been made to tax energy wasters and feed that money towards homeowners insulating and providing their own power.;

A newly constructed apartment complex in Newport News, Va., proves that that future may already be on the way. The Radius Urban Apartment complex windows fabricated with Solarban 70XL glass and SunClean self-cleaning glass by PPG Industries. That’s right, windows that will shrink your energy bill and clean themselves. And they’re both Cradle-to-Cradle certified.

According to the company, Solarban glass is a transparent solar-control, low-emissivity glass that lets light through while also acting as thermal insulation. By transmitting high levels of daylight while blocking the sun’s heat energy, windows made with Solarban 70XL glass can reduce summer cooling costs by as much as 25 percent. PPG also claims that Solarban 70XL glass can cut furnace heat loss through windows in half, which can lower heating bills significantly in the winter months.

And now for the best part: SunClean glass is formulated with a proprietary coating that becomes “photocatalytic” and “hydrophilic” after prolonged exposure to sunlight. Photocatalysis enables the coating to gradually break down organic materials that land on its surface, while hydrophilicity causes water to sheet when it strikes the coating so that decomposed materials are naturally rinsed away when it rains.



Creed ; Creed and Creation: A simple guidebook for running a greener church, Gillian

Straine & Nathan Oxley, Aldgate Press, 2007

Department of Energy and Climate Change (DECC);  Accessed 25/01/2013

Heat-Exchange Systems.

National Archives; Accessed 25/01/2013.


RESATS; Accessed 26/01/2013

Telegraph – radiators  Accessed 27/01/2013.

Links and Resources;

Dublin Heritage-Conservation

Heat loss for engineers;

How to get free cavity wall and loft insulation; It’s not too late to get free insulation installed in your home. And if you’re on a low income or benefits, you could get cash or vouchers as well.

Don’t qualify? You can still save on insulation: If you don’t qualify for free insulation for whatever reason, you can still get discounted installation with all of the major energy companies, and others such as Sainsbury’s Energy.

A detailed guide to insulating your home. ExternalWall Insulation Systems (EWIS) can be used on new or existing buildings;

Sempatap Thermal Solid Wall Insulation Materials & Tools;

Passive House (Passivehaus); For passive construction, prerequisite to this capability is an annual heating requirement that is less than 15 kWh/(m²a) not to be attained at the cost of an increase in use of energy for other purposes (e.g., electricity). Furthermore, the combined primary energy consumption of living area of a European passive house may not exceed 120 kWh/(m²a) for heat, hot water and household electricity. The combined primary energy consumption of living area of a standard house is approximately 220 kWh/(m²a) for heat, hot water and household electricity. External Links for more information: and  More info on ‘passivehaus’; The main design features of passive homes include: –

  • Positioning of homes and buildings to avail of free solar energy. Orientation and selection of the correct site for your home is imperative. Proximity to and height of adjoining buildings can reduce your solar gain.
  • Higher levels of insulation help reduce the cost of heating.
  • Air tightness of your home is crucial in keeping all that free solar energy within the home.
  • Locating the majority of your windows on south facing elevations and reducing the size of any north facing windows.
  • As your home is now extremely air tight, mechanical ventilation will need to be introduced. By ensuring that this ventilation has heat recovery the incoming fresh air shall be preheated by the extracted air. This simple measure helps keep your home warm without having to reheat the fresh air.
  • Correct detailing of junctions between the external fabric and windows and doors to reduce heat loss.
  • Introducing solar panels will help produce approx. 70% of your required hot water once sized correctly and positioned to face south to optimise the solar gain.
  • Other simple measures such as using A rated kitchen appliances and fitting low energy light bulbs will help ensure your new home is both comfortable and warm to live in.


Ireland; Better Energy Homes Scheme; see:-

UK; Solid wall insulation – Energy Saving Trust

Solid Wall Insulation Grants, Home Insulation Grants;

Cavity wall insulation –  Homes – Energy Saving Trust;


Air-pressure Testing;

Reasonable behaviour;

Make sure that there are no unnecessary obstructions in front of radiators, heaters and air ducts. · Bleed and clean your radiators on a regular basis to ensure water circulates properly. Clean off the fluff and dust from the grill and filters of convector radiators and heaters.  Install thermostatic radiator valves (TRVs) to prevent spaces from becoming overheated.

Air Seal

A gap of just 1/8 of an inch under a 36-inch door lets in as much air as having a 2.4 inch wide hole in the wall. Since people often adjust the thermostat and leave heat running longer when they feel a draft, preventing air infiltration can greatly reduce energy usage. Sealing up those cracks will make you feel comfortable and keep more money in your pocket. Remember for every cubic foot of heated or cooled air (that you have paid to condition) that leaves your house, one cubic foot of outside air enters!

Looking for just one thing you can do to improve your home’s energy efficiency? Significantly reduce air infiltration. Gaps or cracks in a building’s exterior envelope of foundation, walls, roof, doors, windows, and especially “holes” in the attic floor can contribute to energy costs by allowing conditioned air to leak outside.

Most Common Sources of Air Infiltration:

  • Bypasses (attic access door, recessed lighting, plumbing stacks, dropped soffits, open frame construction, duct penetrations, electrical penetrations, etc.) in the attic floor regardless of the presence of insulation, which by itself is not an air barrier. If you see dirty insulation, air is getting through.
  • Between foundation and rim joist
  • Crawl spaces
  • Around the attic hatch
  • Between the chimney and drywall
  • Chimney flue
  • Electrical and gas service entrances
  • Cable TV and phone line service entrances
  • Window AC units
  • Mail chutes
  • Electric outlets
  • Outdoor water faucets entrances
  • Where dryer vents pass through walls
  • Under the garage door
  • Around door and window frames
  • Cracks in bricks, siding, stucco and the foundation
  • Mudrooms or breezeways adjacent to garages

How radiators work; Telegraph (UK);

As the water flows through the radiators it gives up its heat to the rooms, thus returning to the boiler at a lower temperature. Designed by the Prussian-born Russian; Franz San Galli

A Low temperature heating system requires a larger surface area to provide enough heat energy. Radiators need to be up to 100% bigger to compensate for the lower temperatures. In other words it contains more mass and area.


London Care of Churches Team

November 2007

The Engineering Toolbox; provides;

1. Heat loss through walls, windows, doors, ceilings, floors, etc.>

The heat loss, or norm-heating load, through walls, windows, doors, ceilings, floors etc. can be calculated as

Ht = A U (ti – to)         (2)

Where; Ht = transmission heat loss (W)

A = area of exposed surface (m2)

U = overall heat transmission coefficient (W/m2K)

ti = inside air temperature (oC)

to= outside air temperature (oC)

Heat loss through roofs should be added 15% extra because of radiation to space. (2) can be modified to:

H = 1.15 A U (ti – to)             (2b)

For walls and floors against earth (2) should be modified with the earth temperature:

H = A U (ti – te)             (2c)

Where; te= earth temperature (oC)

Overall Heat Transmission Coefficient

The overall of heat transmission coefficient – U – can be calculated as

U = 1 / (1 / fi + x1 / k1 + x2 / k2+ x3 / k3 +..+ 1 / fo)             (3)

Where; fi = surface conductance for inside wall (W/m2K)

x = thickness of material (m)

k = thermal conductivity material (W/mK)

fo= surface conductance for outside wall (W/m2K)

The conductance of a building element can be expressed as:

C = k / x         (4)

Where; C = conductance, heat flow through unit area in unit time (W/m2K)

The thermal resistivity of the building element can be expressed as:

R = x / k = 1 / C         (5)

Where; R = thermal resistivity (m2K/W)

Using (4) and (5), (3) may be modified to

1 / U = Ri + R1 + R2 + R3 + .. + Ro             (6)

For walls and floors against earth (6) should be modified to

1 / U = Re + SR             (6b)

2. Heat loss by ventilation

The heat loss due to ventilation without heat recovery can be expressed as:

Hv = cp ρ qv (ti – to)         (7)

Where; Hv = ventilation heat loss (W)

cp = specific heat capacity of air (J/kg K)

ρ = density of air (kg/m3)

qv = air volume flow (m3/s)

ti = inside air temperature (oC)

to = outside air temperature (oC)

The heat loss due to ventilation with heat recovery can be expressed as:

Hv = (1 – β/100) cp ρ qv (ti – to)         (7)

Where; β = heat recovery efficiency (%)

An heat recovery efficiency of approximately 50% is common for a normal cross flow heat exchanger. For a rotating heat exchanger the efficiency may exceed 80%.


About pfiddle

Fiddle teacher - mostly Irish trad. Fiddle, mandolin and concertina. Eco-warrior, won E.U. Green Flower Award for Eco Accommodation. Also Irish (Gold) GHA. Green Hospitality Award. Mad keen on self-build - especially straw-bale and cob. 55 with a full head of (slightly) graying hair. No tattoos or piercings. Fond of animals - but legally so. Fond of food - I eat nothing else. Vegetarian by choice, Irish by the grace of birth, Munster by force of (rugby) arms.

2 responses »

  1. This specific blog, “Sustainability in Older Buildings.

    | Glenribbeen – The Eco-Blog” ended up being very good.
    I am making out a backup to clearly show my personal buddys.
    Thanks for your time-Luciana

    • Happy you liked it. I put it together very quickly for my son – studying stone-conservation in UK. It’s not really my specialty. I hope to build a straw-bale house that will be off-grid and contain at least one self-catering apartment for tourists. Near Dungarvan, Co Waterford, Ireland. More information on LinkedIn.


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