Page 99 - Low Temperature Energy Systems with Applications of Renewable Energy

88 Low-Temperature Energy Systems with Applications of Renewable Energy

the quality of indoor air in schools increases the productivity of school work with an
increase in the flow rate of ventilated air from 5 to 10 L/s; an increase in air flow rate to
25e30 L/s increases labor productivity in an office; and an increase in air flow rate in
living quarters reduces the number of asthmatic and allergic diseases by 2e4 times.
Therefore, to ensure sanitary and hygienic living conditions, good ventilation
3
(w30 m /h per person) with fresh, cold, outside air is required.
Worldwide practice of specifying requirements for energy efficiency in build-
ings varies widely. The following are features of implemented building projects:
complex designs, including modern architectural solutions and technologies of
construction, construction materials and effective climate technology, and intel-
ligent control and management systems. For example, in Scandinavian countries
the requirements for energy-efficient heating and ventilating systems in buildings
are as follows:

• Use of low-temperature heat of return water from the heat supply system for floor and wall
panel radiant heating.
• Use of heat of exhaust air.
• Individual mechanical ventilation with separate heat recovery in each apartment of a multi-
unit, multi-story building.
• Increase in efficiency of natural ventilation.
• Ventilation of premises with preheated outdoor air coming through specially designed
windows.
• Use of low-temperature heating systems.
• Use of solar collectors to heat water.
• Individual control of air temperature in each room.
In individual houses and multi-unit apartment buildings, heat pumps are mainly
used in water heating and hot water supply systems. In this case, natural sources of
energy such as ambient air, water, ground, and solar radiation can be mainly used
as low-temperature heat sources for heat pumps systems along with captured heat
from ventilation air.
The realization of the “energy efficient house” concept is possible by applying mod-
ern technologies of architecture and construction, various renewable energy sources (sun,
wind, ground heat, etc.), and high-tech engineering equipment (Fig. 3.1). The main
feature underlying the concept of a passive house is the use of heat pump technology.
Actual energy efficient buildings meet these requirements. Figures 3.2 and 3.3 show
the architectural solutions of energy-efficient buildings resulting from high-technology
construction.
However, there arises a dilemma between the quality of the architectural environ-
ment and the creation of healthy and productive workspaces, and the creation of low-
temperature energy consumption systems. This requires compromise and optimization
in the building design.
World experience in selling heat pumps shows that about 70% of them are installed in
individual residences. When heating individual houses, various types of heat pumps
can be used, such as air-to-air, air-to-water, ground-to-water, and water-to-water
systems.