A THERMAL INSULATION BYMAW

Press, Volume CXVI, Issue 34123, 8 April 1976, Page 11

A THERMAL INSULATION BYMAW

i (.ontr ibuied by RRIAN BI.LICK, or: behalf of the Clin.'ti hitri ii < ir y < ..

r The Municipal Corporations Act and the Counties Act both empower local authorities to adopt bylaws “ . . . controlling the construction and repair of buildings ...” and “ . . . conserving public health, safety and convenience ...” i In the early 1970 s both the Waimairi CountyCouncil and the Christchurch City Council felt that a by-law which specified a certain amount of thermal insulation for residential dwellings would not only come within the scope of subi jects for which by-laws may be adopted but [ would also make some contribution to the conservation of energy re-

sources — a consideration which ha now become much more significant. By-laws are not rules that are thrust upon ...i unsuspecting public. T! e same Acts which allow by-laws to be adopted also specify how those by-laws shall be adopted. The intention to adopt a by-law must be advertised and any objections considered. As the final document may be subjected to legal action it must also be “reasonable” in the eyes of the court. If it is not. then it may be difficult to ensure that the by-law requirements are complied with. All builders use the present building by-laws not only because they are law but also because they are a statement of “good trade practice.” The sizes of timber rafters and joists required by the bylaws are sizes which have been shown by many

years of experience to be adequate. If a by-law proposes a standard which is a significant change from common practice then the reasonableness of the bylaw may be challenged. When the Christchurch Cit> Council thermal insulation by-law was ad- \ crtised no formal objections were received and subsequently the standard of insulation installed by many builders has been in excess of the minimum by-law standard. This fact in itself would suggest that the present by-law could be considered to be. “reasonable." In general the by-law is worded in such a way that only the standard of performance required is specified. Any thermal insulation system which complies with that standard will comply with the by-laws, independent of the combination of materials used. The standard of ther-

mal insulation spec, d in the Christchurch C::> Council and Waimairi County Council by-.aws has allowed most conventional methods of construction to be used with minor modification. Generally this has meant that undesirable side effects, which could have resulted from the use of new materials and methods without adequate product research, has been avoided. The possibility of sideeffects highlighted the need to ensure that before any insulating systems were approved sufficient technical data was available to enable a realistic assessment to be made. The principal sources of such data have been the Department of Scientific and Industrial Research, and the Building Research Association of New Zealand. This information has been supplemented by product manufacturers

v. ho ha' e produced sufficient trade literature describing the proper way to use their products. Ihe most difficult problem associated with insulation has been the tendency to blame insulation for condensation and mildew problems. In fact condensation will always be a consequence of inadequate ventilation and t ! ■ problem has been agg: ivated to a certain extern t>\ the demise of the For ail its faults the open fire did induce about eight air changes an hour and as a result high humidities were avoided. With no fireplaces and the high qua! ity of modern joinery the air and its moisture are trapped in the house as a humid mixture. When the air temperature drops in the early hours of the morning the moisture shows as condensation. While it is natural to

attempt to save a much “valuable warm air' as possible this must not be done to such an extent that moisture cannot Ire removed from th, loom. Steam Horn showers is a significant moisture source.

If both husband and wife are working, and the home is locked for security reasons, this moisture is never vented to die outside. Regular use of opening windows will help but the most positive way of preventing condensation is to remove moist air at its source, preferably by means of an extract fan which will not cause undersirable draughts.

Insulation will tend to raise the temperature at which epndensation problems occur but will not cure the problem.

The conservation of fuel resources is now a matter of national concern and it is likely* that in the near future a National Thermal Insulation Standard for Buildings will be introduced. This standard will probably* require a much higher standard of thermal insulation than the present Christchuch City Council by-law. To achieve this standard new methods of construction may have to be developed and this development will have to accept that wall and roof systems have multiple functions. They must be weatherproof, durable. structurally adequate, and must now have an adequate thermal insulation performance. New systems must therefore not only satisfy higher thermal insulation standards but they must also be weatherproof, durable and structurally’ adequate and be able to meet these criteria without a significant increase in cost. Many technical problems still have I to be solved. Do heavy walls have thermal storage characteristics which are not acknowledged at present? How many air changes per hour must be provided for the average residence if condensation and mildew problems are to be eliminated? Provided that changes are made gradually, with the co-operation of the building industry, and in the knowledge that even “experts” do not know all the answers, solutions will be found to such problems and significant energy savings will be made.