Sharp JX-9400 Technical Information PDF herunterladen (Seite 128)

a rotating heat exchanger (see Chapter 6, ‘Rotating heat exchangers’), has a

negligible eﬀect on energy demand.

Inﬁltration or exﬁltration through a leaky building envelope strongly

reduces the eﬃciency of heat recovery (see ‘Eﬀect of leakages and shortcuts

on heat recovery’, above). With a heat recovery eﬃciency of 75 per cent, the

heating energy demand for cold and mild climates (Oslo, Zu

rich, London) is

approximately 3–5 per cent higher with an eﬃciency of 0.75 than with 0.85.

For warm climates (Rome), this number is approximately 15 per cent higher,

however, with low absolute values.

Ductwork

An increase of pressure diﬀerence from 1000–1600 Pa, caused by air velocity,

length, curves, duct wall smoothness and deposits in the ducts, leads to an

increase in electric power use of 60 per cent. The increase in total electric

power depends on the geographic location and ranges from 25–55 per cent.

Notes

1 Natural ventilation can be controlled by installing (automatically or manually) adjus-

table vents in an airtight building envelope.

2 These ratios take not only density and heat capacity into account, but also practical

temperatures.

Measurements and Measures Related to Energy Eﬃciency in Ventilation 107

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Sharp JX-9400 Technical Information Seite 128