Utility energy consumption

Increasing the chosen value of process energy consumption also increases all temperature differences available for heat recovery and hence decreases the necessary heat exchanger surface area (see Fig. 6.6). The network area can be distributed over the targeted number of units or shells to obtain a capital cost using Eq. (7.21). This capital cost can be annualized as detailed in App. A. The annualized capital cost can be traded off against the annual utility cost as shown in Fig. 6.6. The total cost shows a minimum at the optimal energy consumption. 

If the network is optimized at fixed energy consumption, then only loops and stream splits are used. When energy consumption is allowed to vary, utility paths also must he included. As the network energy consumption increases, the overall capital cost decreases. 

Increased heat utilization does not always mean a trade-off, and many studies have shown a reduction in energy consumption as well as capital cost which in itself is a remarkable recommendation for a systematic approach to network design. 

Traditional air curtains, which utilize only indoor air heated in the curtain heaters, are not always economical (due to considerable thermal energy consumption). Reduction of heat consumption is achieved by curtains that utilize unheated indoor or outdoor air, and also combined air curtains, which heat, 3only part of the supplied air. Air curtains that use unheated air conserve. 30-70% of thermal energy. 

A characteristic of many industrial halls is that zones of occupancy take up only a small portion of the room volume and height. In addition, the flows are normally buoyancy dominated. This results in a vertical temperature stratification that can be utilized for room air conditioning design in order to achieve effective climatization along with low energy consumption. 

Caiciiiations can be sensitive to the interest rate (Fig- 16.2) and the time ol the calculation period (fig. 16.3), which is the utilization time or the life cycle of the device. Thus, it is often advisable to consider sensitivity analysis for these factors. Elements of uncertainty can also be found in the estimation of energy consumption and investment (in design phase at the pre-tender stage). 

During prolonged heat waves which can cause blackouts and brownouts, electric utilities always request that customers limit energy consumption by raising thermostats and turning off the air conditioning when not home. It is uncertain if these requests are heeded, and if they arc, it is uncertain whether conformity is out of altruism (help the utilities) or self-interest (save money). 

Utilities offered financial incentives to customers to reduce energy consumption because it was less expensive than constructing new power plants to meet the growing demand for electricity. 

The benefits of TES include [2] (i) reduced energy costs, (ii) reduced energy consumption, (iii) improved indoor air quality, (iv) increased flexibility of operation, (v) reduced initial and maintenance costs, (vi) reduced equipment size, (vii) more efficient and effective utilization of equipment, (viii) conservation of fossil fuels, and (viii) reduced pollutant emissions. 

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