heat loss

Discusses standards and guidelines used for calculating the heat demand over a heating season. Notes inadequacy of current methods, in particular the inadequate account taken of certain environmental conditions and of particular window constructions. Proposes improved sizing procedure to take into account heat loss due to infiltrating air. Discusses simplifying assumptions. Gives expressions for critical heat output and for the quantity of air infiltrating a room.

Reports comparison of three computer programs designed to calculate room air temperature and heating loads. The programs are:< BRIS - a swedish program using a finite difference method< BYVOK - a norwegian program using the thermal response factor method

Fresh air requirements in individual rooms of an occupied house vary between 0.5 and 2 air changes per hour depending on the number and activity of the occupants. The most common method of ventilation control is by opening windows but measurements show that even quite moderate window opening results in air change rates greater than 2 air changes per hour throughout a house.< Reports measurement of the energy cost of window opening in a test house with a heat loss coefficient of 5 kWh/K day. Finds in a low energy house,controlled ventilation is essential.

Presents the results of an energy-efficiency survey of 25 homes located in Saskatoon, Saskatchewan. Insulation levels in the walls, ceilings and basements were measured and the economics of adding insulation to these areas were investigated. Air leakage of the houses was measured using a pressure test and compared with infiltration rates measured using tracer gas in fourhouses.< Concludes that a major portion of the heat loss (30-40%) in the average home was due to excessive infiltration.

This is a practical handbook for constructing an energy efficient house. Describes energy conservation measures for the reduction of space heating in an average house on the Prairies. Describes conservation measures for a new house which include the improvement of air tightness, insulation, passive solar gainand insulation of window systems. Also describes refitting an older house, reducing energy used to heat water and reducing electricity consumption. Gives a short list of sources of information.

Presents a method of analysis to separately quantify the amounts of heat loss due to transmission and to air infiltration. The analysis is based on daily gas and electricity readings for a flat. Discusses three models for calculating heat losses; the regression model, the static thermal model andthe dynamic thermal model. Only the static and dynamic models have the ability to predict some of the individual terms in the heat balance equation.< Concludes that all three models may be used for a first estimate of the total amount of energy consumption.

Improved levels of thermal insulation for dwellings in W.Germany have substantially reduced thermal transmission losses, so that ventilation heat loss has become much more important component of total building heat demand. Amount of heat appears important enough to justify considering heat recovery from ventilation air residential buildings. Describes 3 examples of exhaust air recovery from flats in an apartment building. Provides details of air change rates.

Describes use of thermography by Fishburn Thermography group ltd. Outlines use of camera and isotherm function. Suggests use of thermography for the detection in walls of heat losses, thermal bridging, wet or inadequate insulation, air infiltration and other defects.

Presents method for estimating the heat requirements of buildings. The method is based on the ASHRAE degree day method with modifications to take into account a) solar radiation incident on a building surface, b) variation of solar energy gained through windows, c) variation of air infiltration withwind speed and inside-outside temperature difference and d) heat generated by inside activity, such as lights, people etc.< Gives sample calculation for a house and compares with calculation by ASHRAE method.

Gives results of a survey carried out in December 1978 on heating and ventilating of dwellings. 2000 men and women were questioned throughout the federal republic. Gives range of dwellings, desired and actual room temperatures, types of windows, frequency and duration-of window opening and the existence of draughts.< Concludes inter alia that heat loss through ventilation is greater than commonly assumed. In particular this heat loss is through leaky windows and ventilated bedrooms.