ASHRAE Journal - October 2020 - 33

TECHNICAL FEATURE

55% higher). Option 4 is much the same as the base case,
with about 95% of the life-cycle cost of the base case.
In terms of capital costs, Option 3 (basic desiccant system) has the highest cost followed by Option 2 (decoupled DX dehumidiﬁcation and chilled water cooling)
followed by Option 4 (hybrid desiccant and chilled water
dehumidiﬁcation). The lowest capital cost is the base
case Option 1 (chilled water cooling and electric resistance reheat). These results, when read in conjunction
with life-cycle costs, show that although the capital cost
of evaluated options may be greater than the base case,
life-cycle cost is hugely dependent on energy consumption costs because of the energy-intensive dehumidiﬁcation process.

Conclusions
Based on the results and discussions presented in
this article, it can be concluded that dehumidiﬁcation
systems cannot be analyzed from a straightforward
approach on the working principle of different systems.
Certain principles or strategies might reduce the system size by reducing the volume of air being treated to
meet latent loads, but a more extensive analysis needs
to be undertaken because of other parameters such as
required ventilation rates, recommended air changes
per hour for acceptable indoor air quality and higher
supply air temperatures to avoid condensation. These
determine the energy consumption and, in turn, the
life-cycle cost of dehumidiﬁcation systems.
Additionally, it is fundamental to ensure that the
dehumidiﬁcation system is capable of consistently
maintaining the required humidity levels at all load
conditions.
The following conclusions can be drawn for dehumidiﬁcation system options for natatoriums in the hot and
humid climate zones presented in this discussion:
* Decoupled DX dehumidiﬁcation and chilled water
cooling with hot-gas reheat condenser (Option 2) provides the lowest energy and life-cycle costs. This conﬁguration can also provide efﬁcient temperature and
humidity controls, with a humidity sensor controlling
the DX system and a temperature sensor controlling the
chilled water cooling coil. However, the DX system must
use a carefully selected modulating compressor with
precise controls to consistently follow the latent load
proﬁle with the hot-gas reheat condenser strategy.
* Desiccant-based dehumidiﬁcation systems that

use an electric heater for regeneration result in the
highest life-cycle costs. However, the hybrid desiccant
and chilled water cooling coil option will be the lowest
energy consumption conﬁguration, provided a sustainable source such as solar heating or other means of free
energy could be used for regenerative heaters. This can
be derived from Figure 2.

References
1. Ribeiro, E., H.M. Jorge, D.A. Quintela. 2011. "HVAC system
energy optimization in indoor swimming pools."Proceedings of the
2011 3rd International Youth Conference on Energetics (IYCE) 1 - 7.
2. Pillai, J., R. Desai, A. Ten. 2018. "Dehumidiﬁcation strategies
and their applicability based on climate and building typology."
2018 Building Performance Analysis Conference and SimBuild 759 - 766.
3. Lochner, G., L. Wasner. 2017. "Ventilation requirements for
indoor pools." ASHRAE Journal (7).
4. ANSI/ASHRAE Standard 90.1-2016, Energy Standard for Buildings
Except Low-Rise Residential Buildings.
5. ANSI/ASHRAE Standard 62.1-2016,
Ventilation for Acceptable Indoor Air Quality.
6. ANSI/ASHRAE Standard 169-2013, Climatic
Data for Building Design Standards.
https://bit.ly/3bajige
7. 2019 ASHRAE Handbook-HVAC Applications.
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8. 2017 ASHRAE Handbook-Fundamentals.

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