Re: Taking the Attic out of the Equation

[Guest guest]

Facinating.

1. Did you do a HVAC load estimate?

If so:

1. What method? (ACCA, ASHRAE)

2. What parameters?

3. What was the result?

2. Any problems with thermal expansion contraction on the roof?

Tony

........................................................................... "Tony" Havics, CHMM, CIH, PEpH2, LLCPO Box 34140Indianapolis, IN 46234 cell90% of Risk Management is knowing where to place the decimal point...any consultant can give you the other 10%â„ This message is from pH2. This message and any attachments may contain legally privileged or confidential information, and are intended only for the individual or entity identified above as the addressee. If you are not the addressee, or if this message has been addressed to you in error, you are not authorized to read, copy, or distribute this message and any attachments, and we ask that you please delete this message and attachments (including all copies) and notify the sender by return e-mail or by phone at . Delivery of this message and any attachments to any person other than the intended recipient(s) is not intended in any way to waive confidentiality or a privilege. All personal messages express views only of the sender, which are not to be attributed to pH2 and may not be copied or distributed without this statement.

-----Original Message-----From: iequality [mailto:iequality ] On Behalf Of Arista EngineeringSent: Tuesday, November 07, 2006 6:47 AMTo: iequality Subject: Taking the Attic out of the Equation

In the hot humid climate, venting an attic is an obvious moisture source, and the heat of an attic can easily short cicuit insulation via infiltration, and bring with it a lot of moisture.

Anayways, an on going project of mine, an investment for my retirement is four apartments. With the exception of the of some wood framing holding a sheet rock ceiling, they are all concrete construction including the sloping roofs. Literally my hurricane shelters. There is a 5000 gallon rain water cistern, a drilled well and the site is 10 feet higher than a storm surge of a recent major hurricane. WHat remains to be installed on the exterior id white extruded aluminum brackets to hold ply wood for the garden doors and windows. The glass itself is rated for 140 mph wind pressure but is not impact rated.

My attics are sealed, and I have externally insulated the sloping concrete roof with 1.5 inches of foam, and then had a white standing seam metal roof installed over the foam. This is a year round cooling environment so my goal is to keep the heat out.

Here is a look at the rear or eastern exposure in the AM

Rear view

Western exposure or front

Front view

They are not occupied yet and the air conditioning has not been started up. So far the underside of the concrete roof and the attic air are about 1F warmer than the ambient. I think I am going to monitor the two middle units, one with a small amount of conditioned air being supplied, the other with no air. I will only be measuring for temperature and humidity, not sure what exactly I would get off gassed by.

The AC system will provide ventilation via intermittent positive pressure

[Guest guest]

Your project sound wonderful. Wish I had someplace like this to buy

or lease. May I ask if your air conditioner has a very high MERV

rated filter on it? That seems to be my problem in finding non

moldy living quarters. All the air conditioners have flimsy filters

that don't keep mold out and then the mold spores land in the water

in a/c and create mold in otherwise very clean and well maintained

home.

> They are not occupied yet and the air conditioning has not been

started

> up. So far the underside of the concrete roof and the attic air are

> about 1F warmer than the ambient. I think I am going to monitor

the two

> middle units, one with a small amount of conditioned air being

supplied,

> the other with no air. I will only be measuring for temperature and

> humidity, not sure what exactly I would get off gassed by.

>

> The AC system will provide ventilation via intermittent positive

> pressure

>

[Guest guest]

I support the use of good filters where there is a reason and a good

filter on the air conditioner does make sense. The problem is that no

ordinary space is free of mould and the water must be taken care of.

A filter will not stop things from growing inside the unit. Good

drainage will.

Lloyd

To: iequality

Date sent: Wed, 08 Nov 2006 15:26:10 -0000

Subject: Re: Taking the Attic out of the Equation

Send reply to: iequality

[ Double-click this line for list subscription options ]

Your project sound wonderful. Wish I had someplace like this to

buy

or lease. May I ask if your air conditioner has a very high MERV

rated filter on it? That seems to be my problem in finding non moldy

living quarters. All the air conditioners have flimsy filters that

don't keep mold out and then the mold spores land in the water in

a/c

and create mold in otherwise very clean and well maintained home.

> They are not occupied yet and the air conditioning has not been

started

> up. So far the underside of the concrete roof and the attic air are

> about 1F warmer than the ambient. I think I am going to monitor

the two

> middle units, one with a small amount of conditioned air being

supplied,

> the other with no air. I will only be measuring for temperature and

> humidity, not sure what exactly I would get off gassed by.

>

> The AC system will provide ventilation via intermittent positive

> pressure

>

FAIR USE NOTICE:

This site contains copyrighted material the use of which has not

always been specifically authorized by the copyright owner. We are

making such material available in our efforts to advance

understanding

of environmental, political, human rights, economic, democracy,

scientific, and social justice issues, etc. We believe this

constitutes a 'fair use' of any such copyrighted material as provided

for in section 107 of the US Copyright Law. In accordance with Title

17 U.S.C. Section 107, the material on this site is distributed

without profit to those who have expressed a prior interest in

receiving the included information for research and educational

purposes. For more information go to:

http://www.law.cornell.edu/uscode/17/107.shtml. If you wish to use

copyrighted material from this site for purposes of your own that go

beyond 'fair use', you must obtain permission from the copyright

owner.

[Guest guest]

This is a Cuban Building System, the original owners stopped work in

early 2001, with one unit out of four 85% complete. We bought the

property as is, there were a lot of building materials sitting on

site.

I ran many load calculations, the problem is residential load

calculations do not suit these apartments.

The apartments are in the Caribbean, the load calculation procedure

was based on the CSA F280 standard. The big difference from what I

can tell from ACCA's manual J, is more emphasis is placed on

overhanging eaves, and eave heights above windows, the amount of

shadow etc

Design Conditions ------ a dewpoint of 80F , it never really matters

what the temperature is outside here, what matters is if it is sunny

and if it is the rainy season. I will usually input 92.4 db/82.4 wb

as my old program is dos based and metric.

It never gets much hotter than the low 90s, winters are like a nice

summer day in Canada :-)

Latitude 19.5 N

The reason I say the residential load calculations do not really

apply is they give no credit for reflecting away the heat.

This would qualify as tight construction by local standards given

that the walls are rendered concrete blocks, the attic is sealed, I

do not have to worry about ceiling penetrations.

However the walls are not insulated (except the gable walls of the

attic space). Firring the wall for interior fibre glass insulation

is also condusive to providing habitat for insects, EIFS type

systems are popular.

I will be penalized by the late afternoon sun, and I decided to put

more air to the west end of the apartments than what was calculated

just from feeling the effects of what was happening while we were

building them.

The loads here work out high in comparison to the states, what I

have installed are 'light' 2.5 ton 13 SEER systems, 28,000 at 80/67.

The apartments are just over 1000 square feet, the attic was treated

like an additional room on top of it. I do not anticipate humidity

problems even with a dewpoint floating around 80 for 6 months of the

year. I should have decent run time every hour and will keep the

places presurized while the AC runs.

The roof is actually precast concrete beams in filled with blocks.

The local authorities insisted that we pour concrete with mesh over

top. I have a couple 20 foot containers full of red spanish barrel

tiles that came with the property. I was comptemplating using them

and spraying icynene on the under side of the roof, but opted to try

and keep the heat out in the first place.

No noticeable problems with expansion and contraction. Temperature

should be fairly uniform once the AC is started up.

>

> Facinating.

>

> 1. Did you do a HVAC load estimate?

>

> If so:

>

> 1. What method? (ACCA, ASHRAE)

> 2. What parameters?

> 3. What was the result?

>

> 2. Any problems with thermal expansion contraction on the roof?

>

> Tony

>

> ...................................................................

........

> " Tony " Havics, CHMM, CIH, PE

> pH2, LLC

> PO Box 34140

> Indianapolis, IN 46234

>

> cell

>

> 90% of Risk Management is knowing where to place the decimal

point...any consultant can give you the other 10%â„ 

>

> This message is from pH2. This message and any attachments may

contain legally privileged or confidential information, and are

intended only for the individual or entity identified above as the

addressee. If you are not the addressee, or if this message has been

addressed to you in error, you are not authorized to read, copy, or

distribute this message and any attachments, and we ask that you

please delete this message and attachments (including all copies)

and notify the sender by return e-mail or by phone at .

Delivery of this message and any attachments to any person other

than the intended recipient(s) is not intended in any way to waive

confidentiality or a privilege. All personal messages express views

only of the sender, which are not to be attributed to pH2 and may

not be copied or distributed without this statement.

>

> Taking the Attic out of the Equation

>

>

>

> In the hot humid climate, venting an attic is an obvious moisture

source, and the heat of an attic can easily short cicuit insulation

via infiltration, and bring with it a lot of moisture.

>

> Anayways, an on going project of mine, an investment for my

retirement is four apartments. With the exception of the of some

wood framing holding a sheet rock ceiling, they are all concrete

construction including the sloping roofs. Literally my hurricane

shelters. There is a 5000 gallon rain water cistern, a drilled well

and the site is 10 feet higher than a storm surge of a recent major

hurricane. WHat remains to be installed on the exterior id white

extruded aluminum brackets to hold ply wood for the garden doors and

windows. The glass itself is rated for 140 mph wind pressure but is

not impact rated.

>

> My attics are sealed, and I have externally insulated the sloping

concrete roof with 1.5 inches of foam, and then had a white standing

seam metal roof installed over the foam. This is a year round

cooling environment so my goal is to keep the heat out.

>

> Here is a look at the rear or eastern exposure in the AM

>

> Rear

<http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_Octobe

r/Back.jpg> view

>

> Western exposure or front

>

> Front

<http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_Octobe

r/Front.jpg> view

>

> They are not occupied yet and the air conditioning has not been

started up. So far the underside of the concrete roof and the attic

air are about 1F warmer than the ambient. I think I am going to

monitor the two middle units, one with a small amount of conditioned

air being supplied, the other with no air. I will only be measuring

for temperature and humidity, not sure what exactly I would get off

gassed by.

>

> The AC system will provide ventilation via intermittent positive

pressure

>

>

<http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_Octobe

r/Back.jpg>

>

[Guest guest]

The high MERV filters can be quite effective with the draw back of

being restictive.

The only mold food will be the ceilings and perhaps the furniture or

the kitchen cabinets as the interior walls are concrete as well.

I do not anticipate a humidity problem, I am curious as to how

an 'unconditioned attic' will fare compared to the ones I condition.

Should I end up living in one, I have the blessing and the curse of

being married to a compulsive clean freak. I drive her mental at

times :-)

>

> > They are not occupied yet and the air conditioning has not been

> started

> > up. So far the underside of the concrete roof and the attic air

are

> > about 1F warmer than the ambient. I think I am going to monitor

> the two

> > middle units, one with a small amount of conditioned air being

> supplied,

> > the other with no air. I will only be measuring for temperature

and

> > humidity, not sure what exactly I would get off gassed by.

> >

> > The AC system will provide ventilation via intermittent positive

> > pressure

> >

>

[Guest guest]

I would consider a good filter on the fresh air intake. On some

homes with a difficult path to the exterior, I have used small

inline fantech type of fans to bring in the fresh air. I could do

something like that here and then force the fresh air in through a

good filter, then into the return ducts.

The amount of fresh air is not always rocket science though. It is

come up with a CFM equal to an estimated natural infiltration rate

as the first stab in the dark, then adjsut air flow so you just

notice a slight cool breeze leaving around a cracked open door.

>

> > They are not occupied yet and the air conditioning has not been

> started

> > up. So far the underside of the concrete roof and the attic air

are

> > about 1F warmer than the ambient. I think I am going to monitor

> the two

> > middle units, one with a small amount of conditioned air being

> supplied,

> > the other with no air. I will only be measuring for temperature

and

> > humidity, not sure what exactly I would get off gassed by.

> >

> > The AC system will provide ventilation via intermittent positive

> > pressure

> >

>

>

>

>

>

>

> FAIR USE NOTICE:

>

> This site contains copyrighted material the use of which has not

> always been specifically authorized by the copyright owner. We are

> making such material available in our efforts to advance

> understanding

> of environmental, political, human rights, economic, democracy,

> scientific, and social justice issues, etc. We believe this

> constitutes a 'fair use' of any such copyrighted material as

provided

> for in section 107 of the US Copyright Law. In accordance with

Title

> 17 U.S.C. Section 107, the material on this site is distributed

> without profit to those who have expressed a prior interest in

> receiving the included information for research and educational

> purposes. For more information go to:

> http://www.law.cornell.edu/uscode/17/107.shtml. If you wish to use

> copyrighted material from this site for purposes of your own that

go

> beyond 'fair use', you must obtain permission from the copyright

> owner.

[Guest guest]

Very interesting.

What do you think the emissivity of the concrete is (in-situ)? And could you

change it to control some of the loading?

Tony

...........................................................................

" Tony " Havics, CHMM, CIH, PE

pH2, LLC

PO Box 34140

Indianapolis, IN 46234

cell

90% of Risk Management is knowing where to place the decimal point...any

consultant can give you the other 10%â„ 

This message is from pH2. This message and any attachments may contain legally

privileged or confidential information, and are intended only for the individual

or entity identified above as the addressee. If you are not the addressee, or if

this message has been addressed to you in error, you are not authorized to read,

copy, or distribute this message and any attachments, and we ask that you please

delete this message and attachments (including all copies) and notify the sender

by return e-mail or by phone at . Delivery of this message and any

attachments to any person other than the intended recipient(s) is not intended

in any way to waive confidentiality or a privilege. All personal messages

express views only of the sender, which are not to be attributed to pH2 and may

not be copied or distributed without this statement.

Taking the Attic out of the Equation

>

>

>

> In the hot humid climate, venting an attic is an obvious moisture

source, and the heat of an attic can easily short cicuit insulation

via infiltration, and bring with it a lot of moisture.

>

> Anayways, an on going project of mine, an investment for my

retirement is four apartments. With the exception of the of some

wood framing holding a sheet rock ceiling, they are all concrete

construction including the sloping roofs. Literally my hurricane

shelters. There is a 5000 gallon rain water cistern, a drilled well

and the site is 10 feet higher than a storm surge of a recent major

hurricane. WHat remains to be installed on the exterior id white

extruded aluminum brackets to hold ply wood for the garden doors and

windows. The glass itself is rated for 140 mph wind pressure but is

not impact rated.

>

> My attics are sealed, and I have externally insulated the sloping

concrete roof with 1.5 inches of foam, and then had a white standing

seam metal roof installed over the foam. This is a year round

cooling environment so my goal is to keep the heat out.

>

> Here is a look at the rear or eastern exposure in the AM

>

> Rear

<http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_Octobe

r/Back.jpg> view

>

> Western exposure or front

>

> Front

<http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_Octobe

r/Front.jpg> view

>

> They are not occupied yet and the air conditioning has not been

started up. So far the underside of the concrete roof and the attic

air are about 1F warmer than the ambient. I think I am going to

monitor the two middle units, one with a small amount of conditioned

air being supplied, the other with no air. I will only be measuring

for temperature and humidity, not sure what exactly I would get off

gassed by.

>

> The AC system will provide ventilation via intermittent positive

pressure

>

>

<http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_Octobe

r/Back.jpg>

>

FAIR USE NOTICE:

This site contains copyrighted material the use of which has not always been

specifically authorized by the copyright owner. We are making such material

available in our efforts to advance understanding of environmental, political,

human rights, economic, democracy, scientific, and social justice issues, etc.

We believe this constitutes a 'fair use' of any such copyrighted material as

provided for in section 107 of the US Copyright Law. In accordance with Title 17

U.S.C. Section 107, the material on this site is distributed without profit to

those who have expressed a prior interest in receiving the included information

for research and educational purposes. For more information go to:

http://www.law.cornell.edu/uscode/17/107.shtml. If you wish to use copyrighted

material from this site for purposes of your own that go beyond 'fair use', you

must obtain permission from the copyright owner.

[Guest guest]

To be honest, I would have to look up what the published values are

for the emissivity of typical concretes. The interior finish of the

wall is a sand cement render with a gypsom 'knockdown', a flattened

version of the sheetrock compound 'popcorn' texturing.

My wife pick out that peach colour on the exterior, and to give her

credit she pick one that was reflective with respect to UV,

supposedly 80% reflective. The only colours that were better were

the various whites, and we already had a white roof.

Once I have the AC systems started up, I will see what the inside

surface of the western walls stablizie at in the late afternoon, and

try and work out convection and what is radiating. Not keen on

refreshing my mind on view factors though :-)

The thermal lag is there as expected though, Was a nice cool 77F out

this morning as an overnight low and noticably warmer inside when I

was on site at 7AM. I guess it is ideal for cold desert nights.

> >

> > Facinating.

> >

> > 1. Did you do a HVAC load estimate?

> >

> > If so:

> >

> > 1. What method? (ACCA, ASHRAE)

> > 2. What parameters?

> > 3. What was the result?

> >

> > 2. Any problems with thermal expansion contraction on the

roof?

> >

> > Tony

> >

>

> ...................................................................

> .......

> > " Tony " Havics, CHMM, CIH, PE

> > pH2, LLC

> > PO Box 34140

> > Indianapolis, IN 46234

> >

> > cell

> >

> > 90% of Risk Management is knowing where to place the decimal

> point...any consultant can give you the other 10%â„

> >

> > This message is from pH2. This message and any attachments may

> contain legally privileged or confidential information, and are

> intended only for the individual or entity identified above as the

> addressee. If you are not the addressee, or if this message has

been

> addressed to you in error, you are not authorized to read, copy,

or

> distribute this message and any attachments, and we ask that you

> please delete this message and attachments (including all copies)

> and notify the sender by return e-mail or by phone at 317-752-

6386.

> Delivery of this message and any attachments to any person other

> than the intended recipient(s) is not intended in any way to waive

> confidentiality or a privilege. All personal messages express

views

> only of the sender, which are not to be attributed to pH2 and may

> not be copied or distributed without this statement.

> >

> > Taking the Attic out of the Equation

> >

> >

> >

> > In the hot humid climate, venting an attic is an obvious moisture

> source, and the heat of an attic can easily short cicuit

insulation

> via infiltration, and bring with it a lot of moisture.

> >

> > Anayways, an on going project of mine, an investment for my

> retirement is four apartments. With the exception of the of some

> wood framing holding a sheet rock ceiling, they are all concrete

> construction including the sloping roofs. Literally my hurricane

> shelters. There is a 5000 gallon rain water cistern, a drilled

well

> and the site is 10 feet higher than a storm surge of a recent

major

> hurricane. WHat remains to be installed on the exterior id white

> extruded aluminum brackets to hold ply wood for the garden doors

and

> windows. The glass itself is rated for 140 mph wind pressure but

is

> not impact rated.

> >

> > My attics are sealed, and I have externally insulated the sloping

> concrete roof with 1.5 inches of foam, and then had a white

standing

> seam metal roof installed over the foam. This is a year round

> cooling environment so my goal is to keep the heat out.

> >

> > Here is a look at the rear or eastern exposure in the AM

> >

> > Rear

>

<http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_Octobe

> r/Back.jpg> view

> >

> > Western exposure or front

> >

> > Front

>

<http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_Octobe

> r/Front.jpg> view

> >

> > They are not occupied yet and the air conditioning has not been

> started up. So far the underside of the concrete roof and the

attic

> air are about 1F warmer than the ambient. I think I am going to

> monitor the two middle units, one with a small amount of

conditioned

> air being supplied, the other with no air. I will only be

measuring

> for temperature and humidity, not sure what exactly I would get

off

> gassed by.

> >

> > The AC system will provide ventilation via intermittent positive

> pressure

> >

> >

>

<http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_Octobe

> r/Back.jpg>

> >

>

>

>

>

>

>

> FAIR USE NOTICE:

>

> This site contains copyrighted material the use of which has not

always been specifically authorized by the copyright owner. We are

making such material available in our efforts to advance

understanding of environmental, political, human rights, economic,

democracy, scientific, and social justice issues, etc. We believe

this constitutes a 'fair use' of any such copyrighted material as

provided for in section 107 of the US Copyright Law. In accordance

with Title 17 U.S.C. Section 107, the material on this site is

distributed without profit to those who have expressed a prior

interest in receiving the included information for research and

educational purposes. For more information go to:

http://www.law.cornell.edu/uscode/17/107.shtml. If you wish to use

copyrighted material from this site for purposes of your own that go

beyond 'fair use', you must obtain permission from the copyright

owner.

>

[Guest guest]

As an update to this old post, I moved into one of the apartments in April, the south end unit to be exact.

This is a year round cooling environment, and in April and May, with a 79F db indoor temperature the indoor RH was consistently in the low 40% range.

Spot checking the attic, which is still unconditioned and of course SEALED,the temperature always seemed to be less than 2F higher than the conditioned space below and the RH was always in the mid 50s.

I ended up getting a pair of HOBO loggers and sat one on top of my thermostat and placed one in the attic and took temperature and RH readings every 5 minutes for a week earlier this month. Went through four hot sunny days and 3 days of tropical down pours, and outside of spikes from doing laundry and mopping floors, RH in the conditioned space was consistently under 50% and over the period averaged about 44% with an average dry bulb of just over 80. Daytime was set for 79, night time space was set back one degree.

The attic averaged about 82 F over this time period, a peak temperature of 84.8 and a low temperature of 79.5. Average attic dewpoint was 64F, a little higher than I hoped for.

Attic gets the warmest after the sun sets on sunny days, because of the thermal mass of the concrete roof and another contributing factor to this would be enclosed, surface-mounted incandescent ceiling lights. The sealed attic traps this heat. Does not take too many watts to warm up 4000 cubic feet of air in an attic.

I anticipate that I will be conditioning the attic space with a small amount of air, I have made it my goal to try and limit the dewpoint up there to 60F.

The attic temperature and humidity tracked similar to the temperature and humidity of the conditioned space below. The attic and living space are separated by a sheet rock ceiling on wood joists.

I decided to see how the system worked at lower temperatures in case I ever rent the place to people less acclimatized than my wife , so I pulled the apartment down to 75F, just allowing it to set back from 11:45PM until 6 AM. Nighttime set back has been set at 80, cheap hygrometers with max min memory are saying it has not been warmer than 78F so far at night while I am asleep.

So far the occupied space is holding at a solid 40% RH. I have not ventured to into the attic to observe anything yet, I will be waiting for what the data logger says. I am now praying for a tropical system to come through so I can have a worst case humidity challenge, 81F dewpoint, 82 ambient dry bulb, torrential rain and no sunshine for a few days in a row.

At the earlier higher set point the apartment did well against a worst case humidity challenge.

My wife has been suffering through 'too dry and cold' so she is praying for the rain I am holding out for so that I will let the place warm back up.

After I get my rain, I am going to program a high daytime set back, so I can log how the indoor dewpoint rises. With our fairly constant outdoor dewpoint, I think I can use the moisture as a tracer to work out my natural infiltration rate almost effectively as Mr Fluger's "mothballs in the attic". A Poor Man's Blower Door. During a Daytime set back, the place will be unoccupied and the lids down on the toilet seats

I have a gut feeling that recovering from a Daytime Setback may just use more energy than keeping the temperature constant.

I have the place pressurized when ever the AC system runs, with a simple 4 inch fresh air intake to the return plenum of my air handler. I am embarassed to say that I have not even measured my fresh air rate yet, but anticipate it is 40 to 50 CFM.

I am pretty confident that this sealed attic has drastically reduced infiltration, because of the low humidity I seem to be holding and also just from observing the vent caps of two bathroom fans and the clothes dryer. The back draft flappers of these three vents slightly undulate whenever there is a call for cooling, relieving pressure from inside, almost like watching a trumpet player playing Taps.

So I have been holding a solid 75F and 40% Rh, according to a couple low end thermal hygrometers, I am getting curious as to what the HOBO loggers will report. The only place on this tropical island that I have been in that was dryer have been some server rooms with precision cooling and reheat.

The system I installed was of lesser capacity than calculated , and I believe I could have went even smaller (13 Seer 2 ton) to maintain 75 and possibly even smaller to maintain 79F (1.5 ton). One observation is my long south exterior wall is receiving no direct sunlight. I anticipate December being my peak sun on this wall.

Thermal mass also shifts some heat load to after sunset, system runs perhaps a little bit less during the day and a little more at night.

I will also be logging how some of the interior units with only two outside walls fare. I wrote into the lease that tenants had to run the AC, and stipulated a max set point of 82F. I have two such tenants being frugal and keeping the high setting. They will be getting logged in the near future to see what the interior dewpoints stablize at as well.

For my climate, I am sold on not letting attics become solar collectors and there is no need to be ventilating them with air with high dewpoints.

I also realized that I forgot to insulate the large perimter beams in my attic. So it is like having unisulated concrete walls 16" high around my exposed perimeter, sort of analogous to the wood frame builder not insulating the rim joist/header space.

I will make an effort to check a place with a wood truss roof with icynene, it will take some of the thermal mass out of the equation.

>> > In the hot humid climate, venting an attic is an obvious moisture> source, and the heat of an attic can easily short cicuit insulation via> infiltration, and bring with it a lot of moisture.> > Anayways, an on going project of mine, an investment for my retirement> is four apartments. With the exception of the of some wood framing> holding a sheet rock ceiling, they are all concrete construction> including the sloping roofs. Literally my hurricane shelters. There is a> 5000 gallon rain water cistern, a drilled well and the site is 10 feet> higher than a storm surge of a recent major hurricane. WHat remains to> be installed on the exterior id white extruded aluminum brackets to hold> ply wood for the garden doors and windows. The glass itself is rated for> 140 mph wind pressure but is not impact rated.> > My attics are sealed, and I have externally insulated the sloping> concrete roof with 1.5 inches of foam, and then had a white standing> seam metal roof installed over the foam. This is a year round cooling> environment so my goal is to keep the heat out.> > Here is a look at the rear or eastern exposure in the AM> > Rear view> <http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_October/B\> ack.jpg>> > Western exposure or front> > Front view> <http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_October/F\> ront.jpg>> > They are not occupied yet and the air conditioning has not been started> up. So far the underside of the concrete roof and the attic air are> about 1F warmer than the ambient. I think I am going to monitor the two> middle units, one with a small amount of conditioned air being supplied,> the other with no air. I will only be measuring for temperature and> humidity, not sure what exactly I would get off gassed by.> > The AC system will provide ventilation via intermittent positive> pressure> > > > > <http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_October/B\> ack.jpg>>

[Guest guest]

As an update to this old post, I moved into one of the apartments in April, the south end unit to be exact.

This is a year round cooling environment, and in April and May, with a 79F db indoor temperature the indoor RH was consistently in the low 40% range.

Spot checking the attic, which is still unconditioned and of course SEALED,the temperature always seemed to be less than 2F higher than the conditioned space below and the RH was always in the mid 50s.

I ended up getting a pair of HOBO loggers and sat one on top of my thermostat and placed one in the attic and took temperature and RH readings every 5 minutes for a week earlier this month. Went through four hot sunny days and 3 days of tropical down pours, and outside of spikes from doing laundry and mopping floors, RH in the conditioned space was consistently under 50% and over the period averaged about 44% with an average dry bulb of just over 80. Daytime was set for 79, night time space was set back one degree.

The attic averaged about 82 F over this time period, a peak temperature of 84.8 and a low temperature of 79.5. Average attic dewpoint was 64F, a little higher than I hoped for.

Attic gets the warmest after the sun sets on sunny days, because of the thermal mass of the concrete roof and another contributing factor to this would be enclosed, surface-mounted incandescent ceiling lights. The sealed attic traps this heat. Does not take too many watts to warm up 4000 cubic feet of air in an attic.

I anticipate that I will be conditioning the attic space with a small amount of air, I have made it my goal to try and limit the dewpoint up there to 60F.

The attic temperature and humidity tracked similar to the temperature and humidity of the conditioned space below. The attic and living space are separated by a sheet rock ceiling on wood joists.

I decided to see how the system worked at lower temperatures in case I ever rent the place to people less acclimatized than my wife , so I pulled the apartment down to 75F, just allowing it to set back from 11:45PM until 6 AM. Nighttime set back has been set at 80, cheap hygrometers with max min memory are saying it has not been warmer than 78F so far at night while I am asleep.

So far the occupied space is holding at a solid 40% RH. I have not ventured to into the attic to observe anything yet, I will be waiting for what the data logger says. I am now praying for a tropical system to come through so I can have a worst case humidity challenge, 81F dewpoint, 82 ambient dry bulb, torrential rain and no sunshine for a few days in a row.

At the earlier higher set point the apartment did well against a worst case humidity challenge.

My wife has been suffering through 'too dry and cold' so she is praying for the rain I am holding out for so that I will let the place warm back up.

After I get my rain, I am going to program a high daytime set back, so I can log how the indoor dewpoint rises. With our fairly constant outdoor dewpoint, I think I can use the moisture as a tracer to work out my natural infiltration rate almost effectively as Mr Fluger's "mothballs in the attic". A Poor Man's Blower Door. During a Daytime set back, the place will be unoccupied and the lids down on the toilet seats

I have a gut feeling that recovering from a Daytime Setback may just use more energy than keeping the temperature constant.

I have the place pressurized when ever the AC system runs, with a simple 4 inch fresh air intake to the return plenum of my air handler. I am embarassed to say that I have not even measured my fresh air rate yet, but anticipate it is 40 to 50 CFM.

I am pretty confident that this sealed attic has drastically reduced infiltration, because of the low humidity I seem to be holding and also just from observing the vent caps of two bathroom fans and the clothes dryer. The back draft flappers of these three vents slightly undulate whenever there is a call for cooling, relieving pressure from inside, almost like watching a trumpet player playing Taps.

So I have been holding a solid 75F and 40% Rh, according to a couple low end thermal hygrometers, I am getting curious as to what the HOBO loggers will report. The only place on this tropical island that I have been in that was dryer have been some server rooms with precision cooling and reheat.

The system I installed was of lesser capacity than calculated , and I believe I could have went even smaller (13 Seer 2 ton) to maintain 75 and possibly even smaller to maintain 79F (1.5 ton). One observation is my long south exterior wall is receiving no direct sunlight. I anticipate December being my peak sun on this wall.

Thermal mass also shifts some heat load to after sunset, system runs perhaps a little bit less during the day and a little more at night.

I will also be logging how some of the interior units with only two outside walls fare. I wrote into the lease that tenants had to run the AC, and stipulated a max set point of 82F. I have two such tenants being frugal and keeping the high setting. They will be getting logged in the near future to see what the interior dewpoints stablize at as well.

For my climate, I am sold on not letting attics become solar collectors and there is no need to be ventilating them with air with high dewpoints.

I also realized that I forgot to insulate the large perimter beams in my attic. So it is like having unisulated concrete walls 16" high around my exposed perimeter, sort of analogous to the wood frame builder not insulating the rim joist/header space.

I will make an effort to check a place with a wood truss roof with icynene, it will take some of the thermal mass out of the equation.

>> > In the hot humid climate, venting an attic is an obvious moisture> source, and the heat of an attic can easily short cicuit insulation via> infiltration, and bring with it a lot of moisture.> > Anayways, an on going project of mine, an investment for my retirement> is four apartments. With the exception of the of some wood framing> holding a sheet rock ceiling, they are all concrete construction> including the sloping roofs. Literally my hurricane shelters. There is a> 5000 gallon rain water cistern, a drilled well and the site is 10 feet> higher than a storm surge of a recent major hurricane. WHat remains to> be installed on the exterior id white extruded aluminum brackets to hold> ply wood for the garden doors and windows. The glass itself is rated for> 140 mph wind pressure but is not impact rated.> > My attics are sealed, and I have externally insulated the sloping> concrete roof with 1.5 inches of foam, and then had a white standing> seam metal roof installed over the foam. This is a year round cooling> environment so my goal is to keep the heat out.> > Here is a look at the rear or eastern exposure in the AM> > Rear view> <http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_October/B\> ack.jpg>> > Western exposure or front> > Front view> <http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_October/F\> ront.jpg>> > They are not occupied yet and the air conditioning has not been started> up. So far the underside of the concrete roof and the attic air are> about 1F warmer than the ambient. I think I am going to monitor the two> middle units, one with a small amount of conditioned air being supplied,> the other with no air. I will only be measuring for temperature and> humidity, not sure what exactly I would get off gassed by.> > The AC system will provide ventilation via intermittent positive> pressure> > > > > <http://i32.photobucket.com/albums/d41/a_bee_normal/Apartments_October/B\> ack.jpg>>

[Guest guest]

Arista Engineering:

How high up in house structure did you put fresh air intake and does

the fresh air intake pass through a filter? Here in the Ohio River

valley outside mold counts can get very high in summer so I shut

mine off. I put in TWO 6 inch temporarily so as to dilute an indoor

air problem in house. Although that sounds like alot, both have

tight filter on them so the amount of air actually coming in I'm

sure is alot less than it sounds. Both are going through top of

basement wall but end up on 8 inches above ground which I think is

to low to ground, but both were put through a temporary hole in what

used to be a window and can be converted back to window so I don't

plan to keep two 6 inch of them and also would like to find way to

bring them in from higher off the ground.

Your buildings remind me of suggestions for housing made in Dr

Rae's book on " Optimum Environments for Optimum Health " ,

founder of Dallas Environmental Health Center, Dallas, TX. I wish I

could afford one for myself.

In preparation for removing insulation from my attic to clean it up

(prior to sealing it up), I put plastic shrink wrap over all the

windows to prevent 'debris' from cleanup process from getting down

into house and attic odor cleared out, as noticed by myself and

everyone else that comes over. Even people who used to say they

didn't smell 'anything', but that it just smelled like an " old

house " , now say it smells better (i.e. doesn't smell like an old

house anymore). Some attic air still is getting into basement where

bottoms of outside walls are not sealed well, and have noticed that

house humidity readings are lower since doing this, along with

smelling better. Removal of attic insulation went well, with no

debris or dust coming down into house, as a negative air pressure

was maintained with aid of attic power vent and suction of vacuum

used to suck insulation out and possibly plugging leaks in house by

shrink wrapping the about 30 rope and pulley windows and putting

tyvek paper with masking tape over anything else that looked like it

may leak air. However long term, I don't like idea of drawing the

large amount of air through attic that I am doing with attic fan

since you are dragging alot of dirt and mold through attic space at

same time so plan to turn attic fan off or use it as just passive

vent when work is done. I wish I had not ever ventiliated attic

space as this old 1924 house wasn't built for it. It was

unventilated up until about 6 years ago. However I'd have to redo

whole roof structure to go back to unvented attic so too much

expense.

>

>

> As an update to this old post, I moved into one of the apartments

in

> April, the south end unit to be exact.

>

[Guest guest]

Arista Engineering:

How high up in house structure did you put fresh air intake and does

the fresh air intake pass through a filter? Here in the Ohio River

valley outside mold counts can get very high in summer so I shut

mine off. I put in TWO 6 inch temporarily so as to dilute an indoor

air problem in house. Although that sounds like alot, both have

tight filter on them so the amount of air actually coming in I'm

sure is alot less than it sounds. Both are going through top of

basement wall but end up on 8 inches above ground which I think is

to low to ground, but both were put through a temporary hole in what

used to be a window and can be converted back to window so I don't

plan to keep two 6 inch of them and also would like to find way to

bring them in from higher off the ground.

Your buildings remind me of suggestions for housing made in Dr

Rae's book on " Optimum Environments for Optimum Health " ,

founder of Dallas Environmental Health Center, Dallas, TX. I wish I

could afford one for myself.

In preparation for removing insulation from my attic to clean it up

(prior to sealing it up), I put plastic shrink wrap over all the

windows to prevent 'debris' from cleanup process from getting down

into house and attic odor cleared out, as noticed by myself and

everyone else that comes over. Even people who used to say they

didn't smell 'anything', but that it just smelled like an " old

house " , now say it smells better (i.e. doesn't smell like an old

house anymore). Some attic air still is getting into basement where

bottoms of outside walls are not sealed well, and have noticed that

house humidity readings are lower since doing this, along with

smelling better. Removal of attic insulation went well, with no

debris or dust coming down into house, as a negative air pressure

was maintained with aid of attic power vent and suction of vacuum

used to suck insulation out and possibly plugging leaks in house by

shrink wrapping the about 30 rope and pulley windows and putting

tyvek paper with masking tape over anything else that looked like it

may leak air. However long term, I don't like idea of drawing the

large amount of air through attic that I am doing with attic fan

since you are dragging alot of dirt and mold through attic space at

same time so plan to turn attic fan off or use it as just passive

vent when work is done. I wish I had not ever ventiliated attic

space as this old 1924 house wasn't built for it. It was

unventilated up until about 6 years ago. However I'd have to redo

whole roof structure to go back to unvented attic so too much

expense.

>

>

> As an update to this old post, I moved into one of the apartments

in

> April, the south end unit to be exact.

>

[Guest guest]

The fresh air intake is about 11 feet above grade Barb. Right now I

just have a simple hogs hair filter mainly to catch insects and large

particles in the fresh air stream. The fresh air mixes with return air

and then goes through a 1 inch pleated filter, I could check the 'merv'

rating of that.

No one in the household is allergic to pollens or spores, we spend a

lot of time out in the back patio also.

>

> Arista Engineering:

> How high up in house structure did you put fresh air intake and does

> the fresh air intake pass through a filter?

[Guest guest]

The fresh air intake is about 11 feet above grade Barb. Right now I

just have a simple hogs hair filter mainly to catch insects and large

particles in the fresh air stream. The fresh air mixes with return air

and then goes through a 1 inch pleated filter, I could check the 'merv'

rating of that.

No one in the household is allergic to pollens or spores, we spend a

lot of time out in the back patio also.

>

> Arista Engineering:

> How high up in house structure did you put fresh air intake and does

> the fresh air intake pass through a filter?