This document discusses a study on using a simple solar air collector as a solar dehumidifier for damp housing in New Zealand. The study aims to investigate the feasibility and effects of drying a damp building in winter using a solar collector in a tolerable way for occupants and inexpensively. The model found that on a fine winter day facing north, a solar collector could remove 12.4 litres of water from the building through 21 air exchanges. Drying rates varied based on weather conditions, building orientation, and season. Further work will optimize the design and match experiments with accurate evaporation modeling to validate the approach.

1. Thomas Aldershof
Andrew Coffin
Joanne Purdy
Geoff Austin
Departments of Physics
The University of Auckland
Fluids in New Zealand Meeting
18th February 2016
State house
remediation
experiment
Feasibility of a simple solar
air collector as a solar
dehumidifier for damp
housing

2. Motivation
▹ Reduced maintenance cost
▹ Increased building longevity
▹ Improved living conditions
Mould germination conditions
 Reduced mould growth
Sedlbauer (2001)

3. Public health
Monthly respiratory hospital admissions
Gosai, et. al. (2009)

4. Solar dehumidifier
▸Collect ambient air
▸Heat in solar collector
▸Pump through floor
▸Ventilate to dehumidify
Cold air
Solar collector
Wet air
Warm, dry air
Solar panel

5. Feasibility model
Outside air
conditions
Collector
Indoor air
conditions
Low RH
NIWA
Radiation
High RH

6. Aim of the model
Investigate the feasibility and effects of drying a
damp building in winter
▸Tolarable for occupants
▸Inexpensive to install and maintain
▹Temperature
▹Flowrate
▹Collector
▹Independent

7. Approximations
▸All heat exhange through ventilation
▸Damp house
▸Rapid evaporation
▸Fine day
▸Independent on occupant behaviour

8. Modelling outcomes

9. Fine winter day facing North
(Bormashenko 2015)
Drying and ventilation rates
water removed daily
12.4 litre
In approximately
21 air exchanges

10. (Bormashenko 2015)
Building orientation
Drying by building orientation
in litre of water
Angle East West
30° 11.0 12.3
60° 8.5 10.7
90° 5.7 8.0
DryingRateL/hr
Time hours

11. Winter vs Autumn
DryingRateL/hr
Time hours

12. Drying for different weather conditions
(Smyth, Paxon et al. 2010)
DryingRateL/hr
Time hours
Total drying
in litre of water
Fine day 12.4 L
Average day 6.3 L
Bad day 2.3 L

13. Current and
future work

14. Ardmore field site

15. ▸Heat loss
▸Domestic water load
▸Natural ventilation
▸Accurate evaporation modelling
▸Match experiment
▸Real data based simulations
Extend model

16. Optimisation
▸Introduced air conditions
▸Air exchanges per hour
▸Collector specifications
▸Air in- and outlet geometry

17. Conclusion
▸Up to 12 kg of drying
▸Drying occurs under non-ideal conditions
▸Achievable with inexpensive materials
An inexpensive roof mounted solar collector is likely to be a
feasible option to dry moist buildings and thus improve
occupant and building health

18. Andrew Coffin
Joanne Purdy
Geoff Austin
Departments of Physics
The University of Auckland
Thanks!