The Problem of Temperature Control
The problem of maintaining a satisfactory working temperature in a kitchen is more complicated than the provision of adequate heating in a classroom or office. This is mainly because there are in the kitchen many pieces of equipment which during operation themselves contribute heat in varying amounts. The total amount of heat supplied varies from hour to hour according to the amount of equipment in use and the rate at which the heat is produced. The efficiency of the insulation of the equipment is also important in this respect. This is very obvious when one considers the amount of heat radiated into the kitchen by the old-fashioned type of solid fuel range and compares this with the almost complete absence of radiant heat from the heat storage type of cooker such as the Aga or Esse, where a very efficient system of insulation is used. But it is not only in equipment using solid fuel that the value of good insulation is apparent: it is also important when the fuel is gas or electricity; but even so, the extent to which manufacturers have failed to prevent heat radiation from equipment with sometimes unfortunate effects on the temperature of the kitchens is amazing. The case of the kitchen where a temperature of 90°F was found even under controlled conditions of ventilation has already been mentioned. The chief reason for this high temperature was the amount of heat radiated by the outside surface of the gas ovens. The ovens which were new, were supplied by a well-known firm and presumably the engineer who planned the ventilating system underestimated the heat which would be emitted by these surfaces.
The problem is a complicated one because the heat is from three different sources, namely direct radiation from oven walls, hot cupboards and solid top cookers, steam from boilers and steaming ovens and the convection of hot air around appliances. When both temperature and humidity are high, discomfort is experienced by workers because natural evaporation from the skin is diminished. Thus for certain periods of the day the problem of maintaining a satisfactory temperature may be one of cooling rather than of heating, and it thus becomes mainly a question of ventilation. The problem of cooling may be intensified in kitchens drawing air from the dining room as part of the ventilation system. The heat from the dining room can add considerably to the temperature of the kitchen particularly during meal times. This is most noticeable in basement installations. An increase in the number of air changes per hour at peak periods may be the answer. But this alone clearly cannot produce a cool kitchen on a day when the outside temperature is higher than that considered satisfactory for kitchen work. The only solution in such a case would be found in a kitchen with a controlled system of ventilation and air conditioning.
So far the kitchen has been considered as though all parts were affected by the heat given off by cooking equipment. But frequently there are parts that do not receive this heat. One example is the vegetable preparation section which is usually damp in addition and needs special consideration when the heating system is being planned.
(a) There are two separate issues to be considered when deciding the temperature requirements in the kitchen. The first is related to the worker and the second to the material she is handling. A person doing active or moderately active work can perform such work comfortably at temperatures ranging from 55°F to 65°F, and even up to 75°F. little discomfort is felt. Much of the material she handles in her work of preparation and cooking is also dealt with very satisfactorily at these temperatures. Some, however, such as pastry, require the lower range of temperatures for best results, and others, such as yeast mixtures, are better dealt with at the high temperatures. These higher temperatures are also preferable in the servery to prevent undue cooling of the food during service.
(b) The question of maintaining a satisfactory temperature during non-working periods is a straightforward one and is bound up with three issues only, all of which have a bearing during the winter months. At this period the temperature must be maintained at not less than 50°F. If temperatures are lower than this when work commences in the morning there will be complaints of the cold and in addition, the atmosphere will quickly become misty when boilers and steamers are started up. The third point is the prevention of freezing of pipes in frosty spells.
To sum up, the question of heating in the kitchen is largely one of maintaining satisfactory conditions during non-working periods which of course need not attain the same standards of comfort as are called for during working hours.