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Sara Martins Batista
Professor John Odhiambo Onyango
ARC 582 – Special Problems
5 August 2015
Climate Change Adaptive Retrofit Strategy For Buildings In Hot-Humid Climates
What is retrofit?
Retrofit is to add and/or modify something already manufactured/built to its best
resolution. Retrofit strategies are, for architecture, the strategies that add to the building a
design change after its construction. These changes could be for regulative norms and/or
because that building is not fully corresponding to its initial intended proposal. For
instance, retrofit solar heating to a house with bad or poor insulation.
What is climate change?
Climate change is the long-term change in the Earth’s climate, the increase on the
average atmospheric temperature. For example the melting glaciers are the result that the
Earth’s average temperature is increasing, getting hotter, thus the glaciers melt.
According to ESS (Environmental Software and Services, 2015), there are two
‘main groups’ that cause climate change: driving forces and emissions. The driving
forces are world economy and population development; and the “emissions” are energy
system and land use.
In terms of world economy and population development there are growth,
distribution and technology. As the population develops it changes the scenario where we
leave in physically and economically. It affects the number of people in the society, the
distribution of this population around the globe, and the technology created “to support”
our needs and desires. All those three combined together can generate the crowded cities,
powerful financial centers with a huge amount of assets concentrated on hands of few
people, and the opposite: poverty, and remote villages without information,
industrialization, and technology.

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In terms of energy system and land, their effect on climate change it is based on
their usage. “The impact of future energy use will largely depend on the fuel type.” (ESS,
2015) Thus, nowadays we are seeking even more for non-fossil energy sources. For land
use, we need to associate it with world economy and population development. There are
various and different types of land use, and it changes according to demands for food,
which is directly related to population growth (ESS, 2015).
What are hot-humid climates, and how they interfere on the design?
Hot-humid climates are the combination of high temperatures and high humidity.
According to the architect Maitreyi Yellapragada (2013), during summer the maximum
temperature on this climate varies between 27°C and 32°C, and the minimum varies
between 21°C and 27°C, and during the winter those temperatures vary very little. The
humidity is about 75%, but varies from 55% to 100%. Typically the regions surrounded
by oceans, seas, and bay sides are the places with this climate because of the large
amount of water vapor in the air.
Every design is unique, and has to be appropriate to its surroundings. Designing
buildings for this type of climate is very important to analyze every single detail of the
environment. Is necessary to think about the wind, solar radiation, the site, and types of
materials available for the construction, everything that will interfere on the design. For
hot-humid climates, cross ventilation is indispensable, and also appropriate shading
measurements.
For instance: To make a building efficient, which is the focus of this study, and
considering that its location is on a hot-humid climate, we need to verify how the wind on
the site acts; which is the best orientation of the house according to sun light; how could
we position the pipes inside the walls that receive direct radiation from the sun, so they
could heat the water for showering; how the size of the window will be contributing to
the lighting inside the building and thus, saving from using artificial light; and from what
point the window’s size and/or position will be a heating problem.
The design and its parts

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Every design has its subdivisions, and every division will influence on the “hole
picture.” We need to think of orientation; climate; wall construction, roof, floor;
ventilation; and energy use. All of the parties are connected and depend direct and
indirect of each other.
1. Orientation: It will be determined by the sun.
2. Climate: It will determine types of materials for the construction, the orientation
of the building, the size of windows, energy consumption, etc.
3. Wall construction, roof, and floor: They will be determined by the climate, and
also client’s desire and/or architect’s style.
4. Ventilation: The environment’s ventilation will be determined by the climate, and
the building’s ventilation will be determined by the design, materials used, and by
the building’s proposal/usage.
5. Energy use: It will be determined by the design and the climate.
By briefing analyzing the topics above, we can affirm that climate has a huge role
on the design. It affects decisions on each design, and every single detail thus, is very
important to study the climate to guide you through design decisions on the
constructive process.
On this study we will be discussing two adaptive retrofit strategies for climate
changes in hot-humid climates: geothermal cooling system and radiant cooling.
Geothermal Cooling System:
According to Rick Clemenzi (2012), geothermal system is one of the most
efficient cooling and heating systems available. The system uses the temperature of the
Earth as an energy source. The ground absorbs about half of the solar energy that our
planet receives from the sun, thus the temperature remains as a constant all year
(ClimateMaster, 2015). What is great about geothermal system, also known as ground-
source, is that the Earth’s temperature stays constant, so the energy source is always
available at its best value. Depending on the latitude, ground temperatures range from
45°F (7°C) to 75°F (21°C) (energy.gov, 2012). Rick Clemenzi gives an example on his

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article about Asheville, North Carolina, saying that when the outside temperature is 90
degrees, the ground temperature is 59 degrees, and during the winter when it’s 20 degrees
outside, the ground temperature still the same (59 degrees). Thus, a geothermal system
can provide cooling and heating efficiently because it doesn’t depend on a volatile energy
source as wind, for instance, the
ground temperature is a stable energy
source. On figure 1, it shows basically
how the system works.
Geothermal cooling system
also brings an economic benefit. Some
geothermal facilities have realized at
least 50 percent reductions in the price
of electricity since 1980, according to
the geothermalearthusa.com. Also
according to this website these
facilities can produce electricity for
between 4.5 and 7.3 cents per kilowatt-
hour, which makes them very
competitive with regular fossil fuel-fired power plants.
Taking those numbers above to compare with our environment, which is Miami
area, we can compare them with data from FPL’s website. For residential rates there are
two: residential service, and residential TOU rider. The kilowatt-hour is, for the first one,
between 4.73 and 5.81, and the second one varies between 8.81 and -3.92. On the table
bellow we see those numbers and other costs that may come on the costumers’ bill.
Figure 1 - Simply illustration of the Geothermal Cooling System.
Image from:
http://www.wncgreenbuilding.com/articles/full/go_geothermal
Residential rates, clauses
and storm factors
Effective June 2015
RESIDENTIAL RATE CLASS
Customer
Charge1
Energy
Charge1
< 1,000 kWh/
On-Peak
Energy Charge1
> 1,000 kWh/
Off-Peak
Energy Charge1
Storm Charge3
¢/kWh
Conservation2
¢/kWh
Capacity2
¢/kWh
Environmental2
¢/kWh
Fuel
Charge2
< 1,000 kWh /
On-Peak Fuel
Charge2, 4
> 1,000 kWh /
Off-Peak Fuel
Charge2, 4
¢/kWh ¢/kWh
Residential Service (RS-1) $7.57 4.729 5.811 0.150 0.200 0.635 0.205 2.802 3.802
Residential TOU Rider (RTR-1)4
$11.90 8.810 -3.919 0.150 0.200 0.635 0.205 0.822 -0.422
Outdoor Lighting (OL-1) 2.676 0.887 0.098 0.150 0.070 2.907
FPL Owned Units Customer Owned
OUTDOOR LIGHTING
Fixture1
Maintenance1
Base
Non-fuel energy1
Total FPL Owned
Units1
Relamping
& Energy1
Energy
Only1

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As we can see, the geothermal system is not a good solution for Miami area, most
likely because of its humidity. However geothermal system, as we can see during this
research, it is a good solution that brings sustainable and economic benefits.
Another benefit from geothermal cooling systems is that they operate extremely
quietly, and there’s no equipment exposed in the environment giving a 50 percent longer
life expectancy than conventional equipment (Clemenzi, 2012). They need little
maintenance, and do not depend on the temperature of the outside air (energy.gov, 2012).
• How geothermal cooling system works? The process removes the heat
energy of the air inside the building, and moves it into the Earth. This
process involves a cycle of expansion, condensation, compression,
condensation and evaporation (geothermalearthusa.com).
There are four basic types of geothermal systems, also known as geothermal heat
pumps. Three are closed loop systems: horizontal, vertical, and pond/lake; the
fourth type is the open loop. The figures below show a simply sketch of each type
of system.
Figure 2 (left) –
Geothermal closed loop
system – Horizontal.
Image from:
http://energy.gov/energys
aver/articles/geothermal-
heat-pumps
Figure 3 (right) –
Geothermal closed loop
system – Vertical. Image
from:
http://energy.gov/energys
aver/articles/geothermal-
heat-pumps
Figure 4 (left) –
Geothermal closed
loop system –
Pond/Lake. Image
from:
http://energy.gov/ener
gysaver/articles/geothe
rmal-heat-pumps
Figure 5 (right) –
Geothermal open loop
system. Image from:
http://energy.gov/ener
gysaver/articles/geothe
rmal-heat-pumps
Table 1 – FPL’s Residential Energy Rates. Image from: https://www.fpl.com/rates/pdf/June2015-Residential.pdf

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Radiant Cooling System:
According to energy.gov, radiant cooling cools a floor or ceiling by absorbing the
heat radiated from the rest of the room. In North America, the region where radiant
cooling may be a good solution of cooling system is the Southwest, but humid climates
can also be a problem as the panels must be maintained at a temperature very near to the
dew point within the house, and the house must be kept dehumidified.
Radiant cooling systems are generally chilled ceiling beams or panels. The ones
located on the ceiling are commonly called “chilled beams,” because differently from
radiant floors, they will not have contact with human heat directly, no one will touch on
their surfaces. Also, radiant panels and beams will not cover the entire ceiling, as radiant
floor will use the whole floor area (Autodesk Sustainability Workshop).
Most of the radiant cooling systems are based on aluminum panels suspended
from the ceiling, and chilled water circulates through them, but there are two types of
radiant cooling systems: ceiling panels and chilled slabs (oorja.in). The chilled slabs
deliver cooling through the building’s structure, and is also known as thermally activated
building systems (TABS). Radiant cooling using slabs can be used in floors or ceilings,
but according to oorja.in, radiant cooling is better when it is installed on the ceiling.
The second type of radiant cooling is the ceiling panel. The ceiling panels are
installed generally on ceilings, but they can also be installed on walls. Also they are
Figure 6 – Radiant cooling using slabs. Image from:
http://www.oorja.in/what-is-radiant-cooling/types-of-
radiant-cooling-systems/

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usually suspended from the ceiling, but can also be directly integrated with continuous
dropped ceilings. They offer faster temperature control, and flexibility (oorja.in).
On the table below we can see a comparison between slab integrated and panels
systems.
Figure 7 (left) – Chilled beams with integrated
light fixtures. Image from:
http://sustainabilityworkshop.autodesk.com/buildi
ngs/radiant-heating-and-cooling

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Across the US the radiant cooling system can give about 30% off on bills
compared to other conventional systems (Oorja, 2014). Two things are pointed out to be
the primarily source of this 30% of savings: less energy required to transport heat transfer
medium (water), and chilled water from this system is typically at 16°C, instead of 7°C of
the conventional HVAC. The figure below gives a simpler explanation.
Table 2 – Comparison between slab integrated and panels systems. Image from:
http://www.oorja.in/what-is-radiant-cooling/types-of-radiant-cooling-systems/
Figure 8 – Less energy used for air handling in Radiant Cooling Source: LBNL. Imagem from:
http://www.oorja.in/what-is-radiant-cooling/advantages-of-radiant-cooling/

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For the Miami area, radiant cooling is not a good solution. Because it can be
affected by the humidity with a risk of condensation, what can cause water damage,
mold, etc., is a limiting factor for the cooling capacity of a radiant cooling system (Oorja,
2014). The surface temperature should not be equal or below the dew point in the space.
In other words, the limit for the relative humidity in a space should be 60% or 70%, and
air temperature of 26°C (79°F) with a dew point between 17°C and 20°C (63°F and 68°F)
(Oorja, 2014).
Conclusion:
As we can see, both cooling systems are very innovative, eco-friendly, and
important, but the neither of them fits to a building located in a hot-humid climate.
However the geothermal cooling system (ground-source) is the best one compared to
radiant cooling. It will use a stable, non-degradable, and inexhaustible energy source,
which is the Earth’s ground temperature. By using the radiant cooling system we will be
depending on humidity, an energy source that is unstable, and too much of it will
interfere on the system’s function or result on its non-function at all.
Geothermal cooling system is the best option if you are looking for having a
system that is sustainable/eco-friendly and that could bring you economic benefits
depending on the construction’s location. Before choosing it as a cooling system, we
need to analyze the humidity and look through bills or any source of data from the costs
of cooling system to see which one will work best, because as we have seen both systems
depend on the humidity direct or indirectly, even though the geothermal system works
with a the Earth’s temperature, and radiant cooling works with wind/air. Geothermal
cooling is a better system than radiant cooling.
References:
• Autodesk Education Community. Radiant Heating and Cooling (2015)
[ONLINE] Available at:
http://sustainabilityworkshop.autodesk.com/buildings/radiant-heating-and-
cooling. [Accessed] 19 July 2015.

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• Oorja Energy Engineering. Types of Radiant Cooling (2014) [ONLINE]
Available at: http://www.oorja.in/what-is-radiant-cooling/types-of-radiant-
cooling-systems/. [Accessed] 18 July 2015.
• Oorja Energy Engineering. How Does Radiant Cooling Work? (2014)
[ONLINE] Available at: http://www.oorja.in/what-is-radiant-cooling/how-
does-radiant-cooling-work/. [Accessed] 20 July 2015.
• Oorja Energy Engineering. Advantages of Radiant Cooling (2014)
[ONLINE] Available at: http://www.oorja.in/what-is-radiant-
cooling/advantages-of-radiant-cooling/. [Accessed] 04 August 2015.
• Energy.GOV. Geothermal Heat Pumps (2012) [ONLINE] Available at:
http://energy.gov/energysaver/articles/geothermal-heat-pumps. [Accessed]
16 July 2015.
• Western North Carolina Green Home & Living Guide. Go Geothermal
(2012) [ONLINE] Available at:
http://www.wncgreenbuilding.com/articles/full/go_geothermal.
[Accessed] 16 July 2015.
• Geothermal Earth USA Heating & Cooling. How Geothermal Works
(2015) [ONLINE] Available at:
http://www.geothermalearthusa.com/how_geo_works.htm. [Accessed] 21
July 2015.
• Environmental Software and Services (ESS). Climate change scenarios
(2015) [ONLINE] Available at: http://www.ess.co.at/METEO/CCS.html.
[Accessed 25 June 2015].
• Slideshare. Architecture in Hot and humid climate (2015) [ONLINE]
Available at: http://www.slideshare.net/maitreyiy/architecture-in-hot-and-
humid-climate. [Accessed] 15 June 2015.
• ClimateMaster Geothermal Heating & Cooling. What is Geothermal
Energy and How Does Geothermal Energy Work? (2015) [ONLINE]
Available at: http://www.climatemaster.com/residential/how-geothermal-
works/ [Accessed] 03 August 2015.

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• Florida Power & Light Company. Rates and Charges (2015) [ONLINE]
Available at: https://www.fpl.com/rates.html [Accessed] 03 August 2015.