climate change adaptative retrofit strategy for buildings in hot-humid climates_sara martins

Batista 1

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.

Batista 2

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

Batista 3

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

Batista 4

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

4-10-2015/34262

1 Base rates as approved by the Florida Public Service Commission in Docket No. 140197.2 Conservation, capacity, environmental and fuel charges as approved by the PSC in Docket Nos. 150002, 150001, 150007 and 150001, respectively.3 Storm charges as filed in a Routine Storm Charge True-Up Adjustment Request in Docket No. 060038-EI.4 Except for customer charge, all rates and charges under Rate Schedule RS-1 shall apply to RTR-1. In addition, the RTR-1 Customer Charge, the RTR-1 Base Energy and Fuel Charges and Credits applicable to on- and off-peak usage apply.

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

Sodium Vapor 6,300 lu 70 watts $4.86 $1.78 $0.78 $7.42 $2.56 $0.78






Mercury Vapor 6,000 lu 140 watts $3.73 $1.60 $1.66 $6.99 $3.26 $1.66



Other Charges

Wood Pole $9.33

Concrete Pole $12.59

Fiberglass Pole $14.80

Steel Pole $12.59

Underground conductors excluding Trenching per foot $0.075

Down-guy, Anchor and Protector $8.99

Base Non-fuel energy Charge (¢ per kWh) 2.676

Batista 5

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/energysaver/articles/geothermal-heat-pumps Figure 3 (right) – Geothermal closed loop system – Vertical. Image from: http://energy.gov/energysaver/articles/geothermal-heat-pumps

Figure 4 (left) – Geothermal closed loop system – Pond/Lake. Image from: http://energy.gov/energysaver/articles/geothermal-heat-pumps Figure 5 (right) – Geothermal open loop system. Image from: http://energy.gov/energysaver/articles/geothermal-heat-pumps

Table 1 – FPL’s Residential Energy Rates. Image from: https://www.fpl.com/rates/pdf/June2015-Residential.pdf

Batista 6

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/

Batista 7

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/buildings/radiant-heating-and-cooling

Batista 8

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/

Batista 9

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.

Batista 10

• 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.

Batista 11

• Florida Power & Light Company. Rates and Charges (2015) [ONLINE]

Available at: https://www.fpl.com/rates.html [Accessed] 03 August 2015.

climate change adaptative retrofit strategy for buildings in hot-humid climates_sara martins

Documents