Glazing Surface Temperature

Glazing Surface Temperature

DISCLAIMER: This is for informational purposes only, I only own an IR Camera and I am NOT a certified thermographer. I know enough to be dangerous, and that is about it!

Here is my attempt at figuring out the glazing surface temperature at Rochester Passive House. I did 2 different scenario's.
                 1) Full Solar Gain - South facing window
                 2) No Solar Gain - Breezeway (north) door glass

Here were my test parameters:

                                         Full Solar Gain:                                 No Solar Gain:

                                 

The difficulty with finding an actual glazing surface temperature is glass tends to reflect quite a bit, so you are not reading the glass temperature, but the temperature of what is reflecting on the glass.

You can see my reflection in this IR Photo. 

To get closer to an actual glass surface temperature I took a scrap piece of paper, and covered half with black electrical tape, and covered the other half with 2 layers of painters tape. I taped this square to near the center of glass and let it sit there for a while. I am going to assume the paper will become the same temperature as the glass.

This is the paper I taped to the glass. I needed to make sure the paper was completely opaque. I used black electric tape for half, and 2 layers of painters tape for the other half. According to FLIR electrical tape has an emissivity of about 0.95. The painters tape is not as shiny (lower emissivity) but I wasn't sure if how the black tape would show a hotter temperature with the solar gain. 

Here is the Solar Gain Photo:

You can see, the black tape is hotter than the painters tape. But both of them are in the 103-106F range. The hottest temperature is not centered in on the black tape because of the angle the sun is hitting the exterior glass.

I have 2 images for the shaded glass

This one was taken roughly 1.5 ft away at a slight angle. It is roughly 65F

This one was taken about 6" away, but you can see how varied it is, there is quite a bit of reflection going on - but the average temperature is about 62 F

Because I was going in and out of the breezeway multiple times, the breezeway door and interior walls may be a few degrees cooler than normal. I took an IR photo of the interior wall, next to the breezeway door and it was 65F. I didn't post it because it is just an orange square - nothing really to see. 

Summary:

IN WINTER EXTERIOR CONDITIONS

Glazing Surface Temperature of South Windows in full sun = 100-105F

Glazing Surface Temperature of Windows in full shade = 60-65F - within 7F of indoor air temperature.

 Someday I am going to do this with an Energy Star Window and compare. 

What is Passive House Comfort?

Superior Comfort is achieved Passively

Passive House is just as much about comfort as it is about energy efficiency. But what is COMFORT?

Passive Houses are ultra comfortable because:

1) They are ALWAYS Draft Free!

2) They are ALWAYS Quiet!

3) They are ALWAYS Let in Lots of Sun Light!

4) They are ALWAYS Warm!

5) They ALWAYS have Fresh Filtered Air!

6) Oh - they are ALWAYS Low Energy!

So lets talk "Comfort" for a minute... While writing this post I did an internet search for images of "Comfort" and after seeing photo's of Mattresses, Bra's and Lasagna and having a good laugh and some internal comments about our society I decided I had to narrow down my search to "Home Comfort".

There were 2 common themes:
Fireplaces, coffee, blankets and snow out the windows

Fireplaces are not exactly Passive House Comfort

So this is a little closer
White, bright, couches and smiles

Now - guess the season... You never know in a Passive House!

So, there is more to comfort than temperature

As mentioned above, the things that effect your comfort include:

• Drafts - either near a heating or cooling duct, or near a window. In the insulation industry, drafts are the most common comfort complaint.
• When the furnace kicks on you get a blast of cold air before it becomes hot. If your furnace is not sized properly you get this event more often than you should.

• You typically feel this if you have inefficient glass (single or double pane) and warm heated air. The warm air will cool off when it hits the window and drop (since cold air is heavier than warm air). The dropping of air is the draft you feel. 

• There are the most obvious drafts you feel that are coming directly from the outside. Through electrical outlets, under the baseboard, under doors, around windows, into the basement, etc. 

• Drafts near chimneys are very common as well. Neither the glass doors nor the flu create a perfect seal. Cold air will drop and be drawn into the house.  

Not in a Passive House. There are no air leaks, there is no furnace, the windows are super insulated and there is no chimney. Drafts are an aspect of comfort that often get overlooked.

• Noise - Have you ever heard a train blow it's horn, or your neighbor's dog bark at dawn on a Saturday or an airplane fly over, or those construction vehicles work near your house? We have all experienced this in a house before. But since we have just learned to live with it we don't realize how annoying these things can be. 

Thanks Floris from 475 HP Building Supply! 

Outside sound is not a problem in a Passive House (as you can hear from the short video from above). There is also no problems with noise from inside either. All of the mechanical equipment in the house is tested to operate almost silently. There is no Jet Engine noise from the bath fans (there are no bath fans), there is no swoosh of water from an upstairs toilet flush in the downstairs walls (from insulated drain pipes), there is no rumble followed by a winding noise from the furnace kicking on (there is no furnace). We have lived in noisy houses all out life and have learned to live with it without knowing we could do something about it. Passive Houses are quiet!

• Daylighting

Another important aspect of Passive House is proper orientation. There is typically a lot of south facing glass. However when you utilize the Passive House windows they can be arranged on any side of the house. While we do utilize some of the passive solar techniques, they are not vital to the success of a passive house. In the Rochester Passive House - EVERY room has a window in it. In fact the 2 long walls of the house face East / West. We did what we could to maximize the southern window exposure and were smart about window size everywhere else. We even added a transom window in the 2nd floor laundry room to give that room some natural light.  

• Surface temperatures (Not just heated floors)

The number one comment we get from clients looking for a high performance house is..."We have to have radiant floor heating". So comfort is obviously important and our clients have done the research and found that radiant heating systems are more comfortable than forced air systems.

The radiant floor heating typically will over heat a passive house. 

Passive House Design utilizes some Passive Solar techniques to help heat the house in the winter - with proper shading to ensure cooling in the summer. 

What exactly is radiant heat transfer? Well, without getting into Planck's Law, Stefan-Boltzmann Law and blackbody emissive power... It is essentially any materials ability to give off or receive infrared energy to other objects within a line of site of each other.

Huh??? 

So in a typical room you are losing your Radiant Energy (body heat) to all of the cold surfaces around you (making you feel cold). Some of the more common surfaces are, the studs (or thermal bridges), the window surfaces, the cold tile floor, the cold granite countertop etc. All of them add up and pull your radiant energy to make you feel cool even when the air temperature is warm.

The idea behind radiant floor heating is warm feet plus a large warm surface in the house will offset all of the cold surfaces to make you comfortable.

Not Needed In a Passive House... ALL of the surfaces are within 6 degrees of each other - Window glass surface, basement slab, interior walls, tile floors, etc. So the radiant losses are never large enough to effect comfort - if anything they allow a lower air temperature to keep you comfortable.

• Odors

How do you remove odors from your house now?

Open the windows

While this will give you the fresh air you need, it doesn't prevent pollen and dust from coming in as well. I'd also say this doesn't work too well in the Winter.

Turn on our Air Purifier

Cleaning the air is another common option. This doesn't however replenish the levels of Oxygen in the house.  Depending on the size of the purifier they also run off of 100 or more Watts. 

Maybe the most common...

Light a scented candle or use a scented aerosol spray to cover it up. 

 

If you don't think Odor Control is part of Comfort who are you kidding! Every Grocery Store I have even been in carries all of these products. If people could just live with the odors there would be no market for them.

There are problems with just covering up the odors - but I don't need to get into that. There are plenty of articles out there that will do that for me.
Article 1
Article 2
Article 3

There are plenty more, but back to fresh filtered air...

Passive House Utilizes a whole house ventilation system complete with heat recovery. This system runs off of 40-50 Watts (depending on if the ground loop pump is operating)

Fresh Air is drawn in from the outside, filtered and conditioned with the air to air heat exchanger. 

In the hottest and coldest months of the year the incoming fresh air is tempered by a glycol ground loop. In the winter it raises the temperature of the incoming air to near 40 degrees. In the summer it lowers the temperature to near 80 degrees (and dehumidifies the air). 

Now the tempered fresh air is filtered again before it enters an air to air cross counter flow heat exchanger. Here it reclaims about 86% of the heat from the stale stinky air from the house. 

The fresh, filtered, warm air is now distributed to the bedrooms and living spaces while the stale air is removed from the kitchen and bathrooms. Once the heat exchange takes place the stale air is blown outside

Every 3 Hours all of the air in the house is refreshed. 

Passive Houses are ultra comfortable because:

1) They are ALWAYS Draft Free

2) They are ALWAYS Quiet

3) They ALWAYS let in the maximum amount of Natural Light

4) They are ALWAYS Warm

5) They ALWAYS have Fresh Filtered Air

6) Oh - they are ALWAYS Low Energy!

Construction Update #3

Construction Update #3

 Well, A lot has been happening since my last post. We have been pushing the interior and exterior work all at once!

Interior Updates

Drywall

Ceilings hung

Bathroom mold resistant drywall

Window drywall returns with Tearaway strip

Primer and Paint

Amish Kitchen Cabinets

 I should write a whole blog post about the kitchen cabinet experience. Dealing direct with the Amish has been interesting, amazing, frustrating and totally worth it! When we 1st met with them there was no showroom, no photos to see and no limitations on what they could do. All they asked for was the Type of wood (Oak, Maple, Birch, Pine, Cherry, Hickory, Walnut, or anything else we would want), dimensions for the kitchen and the dimension for each cabinet and a photo of the style we wanted and they did the rest. A nearby trim carpenter drove them up to the house and they installed them in 1 day. Once the counter top gets installed they will come back and finish the install (We have an upper cabinet that will sit on the counter top). 

Kitchen Island - 48" x 96"

 Breakfast nook - the upper will hold our microwave

Baking Prep Area - There is a bank of uppers to the right of the window that will sit on the counter top (with a pull out drawer for the mixer).

Interior Doors

Staircase (Upstairs and Basement)

The Main Stairs tread will be stained to match the laminate floor. The risers and stringer will be painted to match the trim. 

The Basement stairs will be painted

Basement Walls framed

You can see the cellulose filling the 8" space behind the basement framed wall.

Basement Windows Installed 

The window install detail is much like the above grade wall detail. We installed the window into the framed wall (to ensure it was in the middle of the R-Value of the basement wall). We wrapped the buck in rigid foam and sealed the window to our air barrier. Let me know if you would like more details on this installation.

Exterior Updates

Front Porch Framed and Roofed

The ledger for the front porch was installed over the rain screen

Siding

Trim to be painted white

Front of House (Faces West)

 North Side of the Garage

Back of house 

South side is awaiting a lift to complete the siding on the south 2nd floor and gable

Along with a few more blower door tests we will be installing trim, floors, final grade and water heater shortly! Stay Tuned!