Energy conservation v tight building syndrome

[deek]

Just to clarify a few points to help the discussions along: -

Tight building syndrome is a new name for an old problem. The term was originally known as sick building syndrome. Over recent years the term was altered to reflect the most prevalent and recognised cause of illness of the occupants of buildings (poor ventilation rates). I appreciate that the term is slightly misleading in that it could be implied that this refers to buildings that are air tight, but this is not the case. Tight building syndrome can exist in buildings where the ventilation rates have been designed fully in accordance with technical standards/regulations. The problem with the technical standards is that they only take account of indoor CO2 levels and excess indoor heat build-up. In other words, the recognised ventilation rates within building do NOT take account of VOCs that are present in the indoor environment.

Sick building syndrome was initially found to be caused in buildings fitted with a certain type of specialist ventilation system (phased out many years ago) in office buildings and hospitals; air handling units fitted with hot water humidifiers. These reported health complaints also lead to the term "humidifier fever" that more precisely pinpointed the causal factor.

Around the same time it was discovered that underfloor electric heating systems installed in many buildings were also the cause of reported health complaints. The cause was confirmed to be VOCs emitted from the adhesives used to stick carpets and floor tiles to the floor screed. Also implicated was the carpet backing, bonding agent included in the cement floor screeds. When the underfloor heating was switched on it slowly raised the temperature of the floor screed (heating medium) and this heating would initiate the release of VOCs from the various floor materials. This cycle (if undetected) could last for years.

Later studies confirmed that many, many more products in the indoor environment emitted VOCs e.g. fixtures, fittings, decorating products and furniture, etc., and these are known to contribute to sickness/illness of the building occupants (including residential buildings). The studies also found that increasing the ventilation rates within buildings resulted in fewer complaints of sickness/illness. Many architects conscious of the problems now try to select (and design in) products that are known to be low VOC emitters, but this is not always the case, and aesthetics of the building interior often means that compromises have to be reached. In residential buildings, it would appear that only lip service is paid to low VOC selection due to cost constraints and more probably due to the lack of understanding of the building contractor. This problem is compounded by the future occupants (homeowners/residents) who will introduce their own specific tastes of wall/floor finishes and furniture and have no concept of the health problems that this may cause to themselves and children.

The retrospective solution is simple; increase ventilation rates in residential homes. But this runs contrary to the message being trumpeted by energy efficiency campaigners that draught proofing of housing should be improved (where possible).

Lets put this into perspective, the same homeowner, who thinks he is doing his bit to “save the planet” by draught-proofing his home, is unlikely to open his windows to increase ventilation rates during the winter months. So the moral to the story is; if you want to draught-proof your home then fine, but you should then (to prevent giving rise to illness) open the windows to compensate for the reduced airflow rates that this will cause.

[deek]

BTW; the trickle vents installed in double-glazing units in the UK are only fitted (by the manufacturer) to ensure compliance with the minimum ventilation rates stated in the technical building standards. These should not be considered as an adequate means to increase ventilation rates to remove VOCs or other indoor air pollutants.

The true purpose of the trickle vents is often compromised as the user is provided with the facility to open or close the trickle vents as he/she desires. Again, the homeowner who has listened to the message from the energy conservation campaigners will be unlikely to leave these trickle vents open during the winter months (he will literally feel the draft and then close the vents firmly).

[screener]

In this part of the world the trickle vents would also have the problem of moisture and therefore frost build-up in the winter. This info is from a commercial site but I think answers some of the questions about how to deal with indoor air quality problems.

Modern homes are constructed practically air tight. Older homes have been sealed tighter over the years by the owners with new windows, door seals and caulking. Preventing the loss of indoor air also means that we don't get enough fresh air into the home. This results in health issues as dangerous fumes and gases from common household products (VOCs), unhealthy buildup of radon gases, and mold and mildew. But the Air-to-Air Heat Exchanger corrects that by flushing out stale air and replacing it with fresh air from the outside.

In addition to providing a consistent supply of fresh air, the Air-to-Air Heat Exchanger can help significantly lower heating costs during the winter by transferring heat from the exhaust air to the fresh air stream. In the summer, it also reduces the load on the air conditioner by lowering the temperature of the fresh outdoor air. Once installed, you'll soon realize that it won't cost you as many energy dollars to make your home a comfortable temperature.

Any accomplished do-it-yourselfer can complete the installation in 4-8 hours; no professional installation is needed. The Air-to-Air Heat Exchanger includes a standard 12" x 12" air filter that will need replacing at least every three months of operation; more often in heavily polluted areas. The heat exchanger core, which is easily removable, must be hosed down at least once a year. You can do this in the sink or outside with the garden hose.

The blower motors are thermally protected, the housing has a safety interlock switch, and the housing is a heavy gauge sheet metal.

HE150 Air-to-Air Heat Exchanger

[spadlet]

What about reducing the ammount of VOC emitting substances used? For example you can get low to non existant VOC paints. Could you not remove or minimise the VOC emitting materials when refurbishing a house, reducing the problem?

Software has been/is being developed to model air & heat flows etc within buildings. I'm pretty sure that regulatins for smaller properties, such as most domestic homes, rely on rules of thumb in the guidance whilst the actial law allows people to use their own techniques as long as they can prove that iw will achieve the same aims. For larger buildings computer simulation seems necessary. It would be interesting to find out whether VOC emission and build up is included in the current simulation packages.

[Besoeker]

Originally Posted by screener

If you are heating with a furnace or heater having a flue and the heater is off then the air flow could go the other way unless there is a flap of sorts to prevent that. .

Two nations divided by a common language.....
In UK central heating is common. The heating is produced by the "boiler" - roughly the equivalent of the US furnace in a domestic context.
I don't think either name is particularly apt but that's by the by.
In UK boilers are generally ballanced flue. Inlet and outlet are to the outside world.

[screener]

I think spadlet is right on her estimate of the first things we should do. First minimize the problem with sensible choices for home decor. as much healthy stuff around us as possible.

Central heating should have an exterior inlet but it also helps to have removal of interior air through the combustion chamber. If the boiler or furnace inlet comes through a heat exchanger, and you also have some air going into the living space through the exchanger I think you could see a further reduction in bad air even after doing spadlets suggestions.