Sustainable Building Operation Using Simulation - Low Energy Cooling for Sustainable Buildings - page 220

2500

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500

IEA handbook

0

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300

Cooling power / kW

Figure 6.21 Investment costs of low-power thermal absorption chillers

To obtain the annuity a as the annually occurring costs, the NPV is multiplied by
a recovery factor r f , which is calculated from a given discount rate d and the lifetime
of the plant N . The cost per kilowatt hour of cold is the ratio of the annuity divided
by the annual cooling energy produced:

d ) N

+

d (1

a = NPV × r f ( N, d ) = NPV × (6.14)

+ d ) N

(1 − 1

The investment costs for the cooling machines were obtained from our own market
study (see Figure 6.21). The costs are frommanufacturers based in Germany and from
a survey of the International Energy Agency (Henning, 2004a). A regression through
the data points was used to obtain the costs for the given power used in the calculations.
With a discount rate of 4% and 1.9% inflation costs over a service life of 20 years, the
annuity for the cooling machine alone was D 1518 per year.
In addition to the chiller investment costs, the annuity of the solar thermal systemwas
calculated from the surface-area-dependent collector investment costs, the volume-
dependent storage costs and a fixed percentage of 12% for system technology and
5% mounting costs. Cost information for the solar thermal collectors and storage
volumes was obtained from a German database for small collector systems, from the
German funding programme Solarthermie 2000 for flat plate collector surface areas
above 100m 2 and for vacuum tube collectors from different German distributors (see
Figures 6.22 and 6.23).
Maintenance costs and the operating costs for electric pumps were set at 2%. Major
unknowns are the system integration and installation costs, which depend a lot on the
building situation, the connection to the auxiliary heating or cooling system, the type
of cooling distribution system and so on. Due to the small number of installations,