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.
The overall heat loss from a building can be calculated as
H = Ht + Hv + Hi where H = overall heat loss
Ht = heat loss due to transmission through walls, windows, doors, floors and more
Hv = heat loss caused by ventilation
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.
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 seai.ie/(Power_of_One) ; “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.
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. freeindex.co.uk/air_pressure_testing/
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.
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).
- Search for articles on old house websites such as the Old House Journal
- 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 www.heatinghelp.com
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; http://passiv.de/en/
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; london.anglican.org/Church-heating.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. Renewableenergyworld.com/push-for-homes-to-be-powerhouses
In France A push has been made to tax energy wasters and feed that money towards homeowners insulating and providing their own power.; Renewableenergyworld.com/france-taxing-carbon-emitters-in-an-effort-to-overhaul-consumer-energy-costs
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. Earthtechling.com/self-cleaning-solar-glass-is-a-lazy-mans-dream/
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); https://www.gov.uk/government/organisations/department-of-energy-climate-change Accessed 25/01/2013
National Archives; http://webarchive.nationalarchives.gov.uk/+/http://www.berr.gov.uk/energy/statistics/index.html Accessed 25/01/2013.
RESATS; https://restats.decc.gov.uk/cms/welcome-to-the-restats-web-site/ Accessed 26/01/2013
Telegraph – radiators; http://www.telegraph.co.uk/property/propertyadvice/jeffhowell/8214378/Home-improvements-how-to-heat-the-house-this-winter.html Accessed 27/01/2013.
Links and Resources;
Dublin Heritage-Conservation Dublincity.ie/Planning/HeritageConservation/Conservation/pdf
Heat loss for engineers; http://www.engineeringtoolbox.com/heat-loss-buildings-d_113.html
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. http://uk.finance.yahoo.com/news/free-cavity-wall-loft-insulation-160620453.html
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; http://www.youngdesignbuild.ie/EWIS.html
Sempatap Thermal Solid Wall Insulation Materials & Tools; http://www.youtube.com/watch?v=gKXb9fx9cmw
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: http://www.passiv.de and www.europeanpassivehouses.org 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:- Citizensinformation.ie
UK; Solid wall insulation – Energy Saving Trust .www.energysavingtrust.org.uk
Solid Wall Insulation Grants, Home Insulation Grants; www.governmentgrantssolidwallinsulation.co.uk
Cavity wall insulation – Homes – Energy Saving Trust; www.energysavingtrust.org.uk
Air-pressure Testing; http://www.freeindex.co.uk/categories/industry/industrial_services/air_pressure_testing/
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.
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
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
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
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%.