MI Windows and Doors, Inc.

My windows have storm windows. I am looking at replacing these windows with new ENERGY STAR qualified windows, but they don’t have a storm window. Does not having a storm window reduce their efficiency?

Sat, 09 Feb 2013 00:17:38 GMT

When installed in combination with older, less efficient windows, storm windows enhance efficiency by creating another barrier between the interior of you home and the weather outside. However, ENERGY STAR qualified windows are designed with multiple panes of glass and specialty gas fills, which create an even more effective barrier within the window itself. ENERGY STAR qualified windows also have additional features such as low-emittance (low-E) coatings and high performance frames that enhance efficiency even more. With these features, storm windows are not generally necessary in order to achieve a high level of energy efficiency.

As I look at your patio door configurations, what is the difference between the "OXXO" and the "XIIX"? We are wanting to have our patio doors open all the way to one side or the other.

Mon, 17 Sep 2012 16:46:58 GMT

The X Panel signifies an operating panel. This panel can only slide to the left or right and has a handle to open the door on it. The I Panel is an intermediate panel, which can slide but does not have a handle on it. I believe this is what you are looking for, as when you open one of the X Panels, it picks up the two I Panels along the way and all four panels can be opened to one size.

Window measurements seem confusing. Is a 3050 window 3 feet by 5 feet or 30 inches by 50 inches?

Thu, 23 Aug 2012 16:10:06 GMT

Our measurements for new construction windows are in feet. For example, the 3050 stock size would be 3 ft x 5 ft or 36"x60".

The size guides can be found for some of our new construction products on our website. For replacement windows, we do not have stock sizes and all of the measurements are in inches. If you see a replacement window size of 28x42, that would be 28"x42".

Both of these measurement listings are pretty much industry standard.

Note: If your existing windows have a nail fin, the size of the window does not include the fin. It is the tip to tip frame size. On most vinyl windows, the fin extends 1 ½” past the frame all the way around the window, so to find the tip to tip fin size you would add 3” to the frame size.

What is the difference between Design Pressure, Performance Grade, and Structural Test Pressure

Thu, 24 May 2012 20:04:00 GMT

The terms "Design Pressure", "DP," "Performance Grade," "PG," and "Structural Test Pressure," "STP" have in the past been loosely used by some in the field.

The specific definitions of these terms have been carefully confirmed with the publication of AAMA/WDMA/CSA 101/I.S.2/A440-08, NAFS – North American Fenestration Standard/ Specification for windows, doors, and skylights. Those definitions follow:

Design pressure (DP) – a rating that identifies the load, induced by wind and/or static snow, that a product is rated to withstand in its end-use application. (Not to be confused with performance grade (PG) or structural test pressure (STP).) Loads induced by static snow are applicable only to unit skylights, roof windows, and TDDs.

Performance grade (Grade or PG) – a numeric designator that defines the performance of a product in accordance with this Standard/Specification. (Not to be confused with design pressure (DP) or structural test pressure (STP).) Performance grade (PG) is achieved only upon successful completion of all applicable tests specified in Clause 5.

Structural test pressure (STP) – the pressure differential applied to a window, door system, TDD, or unit skylight. In this Standard/Specification, the STP is 150% of design pressure (DP) for windows and doors and 200% of design pressure (DP) for TDDs and unit skylights. (Not to be confused with design pressure (DP) or performance grade (PG).)

In other words, design pressure and structural test pressure are strictly structural qualifications, irrespective of the results of any air leakage resistance testing or water penetration resistance testing.

On the other hand, the performance grade of a product is limited by the lowest/least performance of its structural, air leakage resistance, or water penetration resistance test results; operating force and/or forced-entry resistance requirements may also apply.

What's the Difference between U-factor and R-value in Energy Efficient Windows?

Mon, 02 Jan 2012 16:36:00 GMT

The biggest difference between U-factor and R-value is that U-factor measures the rate of heat transfer (or loss) while R-value measures the resistance to heat loss.

R-value is a measure of conductivity. A product with high conductivity will transfer heat quickly, like a hot pan on the stove or a single pane of glass on a cold day. U-factor, on the other hand, takes into account more than conductivity. It also is affected by the airflow around the window and the emissivity of the glass.

What is the difference between conduction and convection through windows?

Wed, 07 Dec 2011 20:52:00 GMT

There are several terms that homeowners can familiarize themselves with so they can better understand the science behind energy efficient windows.

They are conduction, radiation, convection, air infiltration, and radiant heat loss.

Conduction: The direct transfer of heat through a window to the outside.

Radiation: The movement of heat through infrared energy through the glass panes.

Air Infiltration: The amount of air that seeps between the window frame and sash.

Convection: When warm air from inside the home meets a cold window, a chilly, circulatory draft can occur

Radiant Heat Loss: Clear glass absorbs interior heat and radiates it outdoors. Low E glass coatings greatly reduce radiant heat loss.

My city requested that I have tempered glass windows. Is this code for southern California? Or does this meet the safety glass minimal standard?

Sun, 04 Dec 2011 13:45:00 GMT

Local jurisdiction always is the last word for tempered requirements for safety glass.

I would guess these windows are made with standard annealed glass (which is not safety glass) and they are too close to the floor, in a bathroom, or near a swinging door. The inspector will be able to clarify what the issue is and a dealer in the area should be able to quote the price for replacement tempered glass panels plus the labor to install them.

Ask yourself these questions about a window you are putting in. If the answer is YES, then tempered – or safety glass is required.

Is the window less than 18 inches from the floor?
Is it a patio door?
Is it a large window more than 9 square feet?
Is the window in a bathroom and close to the bathtub?
Is the window within 3 feet of a door?
Is the actual top of the window within 3 feet of the floor?

But always check your local building codes and your local dealer who will be aware of what these are.

What's the Difference Between Design Pressure, Performance Grade, and Performance Class?

Wed, 26 Oct 2011 19:25:00 GMT

Standards in the door and window industry are constantly evolving due to changes in technology, building codes and rating system performance requirements. This has led to some confusion around the differences between Design Pressure, Performance Grade, and Performance Class.

Design Pressure* (DP) - The Design Pressure Rating represents the maximum positive and negative wind load that a window or door can experience without breaking, deglazing or permanently distorting. The test results are valid for the size unit tested and smaller.

DP Rating is expressed in positive and negative pound per square foot (+/- psf) The test is conducted at 150% of the rating achieved. i.e. a DP + /- 45 psf rated window was tested to a structural load of 67.67 psf.

A Couple of Key Points Regarding Design Pressure:

• Design Pressure should not be confused with Performance Grade and Performance Class. Design Pressure Rating (DP) is the anchoring test and one of several test criteria that make up a window’s overall performance grade. See Ken Benden's article in DWM magazine for more information regarding this topic.

• A building code or architect may only specify DP and not specify an overall performance grade. In these cases the spec is only addressing the wind loads expected to affect the product.

• It is not unusual for a window’s DP Rating to be greater than the overall performance grade rating. In these cases the performance grade was limited by one of the other test criteria such as the water penetration resistance which is conducted by uniformly applying water spray at a constant rate of 5.0 U.S. gal/ft2 • hr to the test unit at 15% of a specified design pressure. The maximum rating is exceeded when water is able to be drawn or pushed over the sill under positive or negative pressures. i.e. a window’s overall rating could be limited by the water test at a DP-30 (15% of 45 psf). That same window could achieve a DP-45 (67.5 psf) in the structural load test. In this case the window’s overall performance grade is PG-30 but the window would also have a secondary rating of DP-45.

• Window Test Size is a critical variable when comparing the DP and overall performance grades of various windows. AAMA 101 specifies minimum gateway sizes to qualify for a Performance Class Ratings of R, LC, C and AW. i.e. the minimum gateway size for a single hung LC performance class window is 44” x 75”. The test results qualify that size window and below. Generally smaller windows will achieve higher results than the same window at a larger size. Some windows are tested at multiple size to satisfy the variety of customer needs. i.e. a window may be tested to DP-45 only at 36” x 60”; a larger sized unit could be tested LC gateway size (44”x75”)at an overall performance of LC-30. In this example a 44”x75” window and below would have a rating of LC-30 and at 36" x 60" and below the DP would be enhanced to a DP-45.

Performance Grade* (PG) - a numeric designator that defines the performance of a product and is a set of performance requirements corresponding to a Design Pressure range.

Performance grade (PG) is achieved only upon successful completion of all applicable tests:

1) Water Penetration Resistance - tested in accordance with ASTM E547 with the specified test pressure applied per AAMA/WDMA/CSA 101/I.S.2/A440-08. The test consists of four cycles. Each cycle consists of five minutes with pressure applied and one minute with the pressure released, during which the water spray is continuously applied. The water spray shall be uniformly applied at a constant rate of 5.0 U.S. gal/ft2 • hr.

2) Air Infiltration Resistance - tested in accordance with ASTM E283 at a test pressure of 1.57 PSF. The allowable air infiltration for R, LC & CW is 0.3 cubic feet per minute per square foot of frame (cfm/ft2).

3) Uniform Load Defection Test - tested in accordance with ASTM F588 (Windows), F476 (Swinging Doors) and F842 (Sliding Doors) at a performance level 10 rating.

4) Operating Force (Operable windows only) - Minimum and maximum operating force vary by product type and performance class.

5) Forced Entry Resistance (Operable windows only) - tested in accordance with ASTM F588 (Windows), F476 (Swinging Doors) and F842 (Sliding Doors) at a performance level 10 rating.

Performance Class - Performance class describes the likely target application for a window. This classification system provides for several levels of performance. Product selection is always based on the performance requirements of the particular project.

There are four performance classes:

R: (Residential), commonly used in one- and two-family dwellings

LC: (Light Commercial), commonly used for low- and mid-rise multifamily dwellings and other buildings where larger sizes and higher loading requirements are expected

CW: (Commercial), commonly used in low- and mid-rise buildings where larger sizes, higher loading requirements, limits on deflection and heavier use are expected

AW (Architectural), commonly used in high-rise and mid-rise buildings to meet increased loading requirements and limits on deflection and in buildings where frequent and extreme use of the fenestration products is expected

Each performance class has a minimum performance grade based on a minimum design pressure for structural capacity, air infiltration resistance or water penetration resistance in order to qualify for that class.

Entry-level (“gateway”) Performance Grades are:

> 15 psf (720 Pa) for R class

> 25 psf (1200 Pa) for LC class

> 30 psf (1,440 Pa) for the new CW class

> 40 psf (1,920 Pa) for the AW class

MI Windows and Doors goes through an extensive testing process with each of it's windows and doors. To see a how MIWD tests its windows and doors, check out the MIWD Testing Video in our Video Library.

More information: http:/aamanet.org/general/2/407/performance-class-overview

*The specific definitions of these terms have been carefully confirmed with the publication of AAMA/WDMA/CSA 101/I.S.2/A440-08, NAFS – North American Fenestration Standard/ Specification for windows, doors, and skylights.
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MI EnergyCore Double Hung Window Sill Design: Pocket Sill or Sloped Sill?

Wed, 19 Oct 2011 17:04:00 GMT

There is an age old debate in the window marketplace over whether a pocket sill or a sloped sill design is superior for a double hung window.

The MI EnergyCore double hung window was designed from the ground up using state of the art computer aided design software, finite element analysis, and thermal analysis. Design considerations like water exfiltration were planned and accounted for to make this one of the soundest window systems available on the market today.

The window uses a hybrid sill design, where the sill has exterior sloped drainage in addition to a taller water column height in the pocket. The weep holes (as shown in the attached image) are only .015” off the bottom wall, so as long as the window is installed properly (level) there should be little to no water left in the sill, and any minute amounts there may be should evaporate with the minimal air movement there will be in the sill.

One of the advantages of the hybrid design is that the bottom sash is trapped in a pocket so that negative load is optimized. In fact, the sill design received a DP 65 (9.82 psf) on water with an overall structural rating of DP40 or DP50 depending on the size of the unit. The air infiltration (AI) value is .09 psf which is 2/3 less than the AAMA allowed .30 psf. Another advantage is that the windows are more secure because the bottom sash is not exposed like it is in standard sloped sill design.

While some window manufacturers use the same frame material to minimize extrusion expense, the MI EnergyCore window's frame has a dedicated hybrid sill extrusion that was designed to take advantage of the benefits of both a sloped and pocket sill. To fabricate the dissimilar frame components to exacting specifications, MI Windows and Doors uses an advanced computer controlled welder and a 4 head, 12 tool CNC corner cleaner.

The MI EnergyCore Window System’s unique design results in a more energy efficient, more secure, stronger and quieter window with traditional style. To see how the windows are made using state of the art processes, see our Video Library and our How It's Made Video.

Your EnergyCore brochure refers to TMAX glass. Do you have information on visual transmittance information on TMAX?

Fri, 09 Sep 2011 19:14:00 GMT

At MI Windows and Doors we offer a variety of glass types to meet different requirements.

Considerations includes climate, sound control, UV protection, and enhanced security.

We offer many different glass types and packages including double and triple pane, and laminated glass, but here are our main three offferings:

TMAX HE™ - TMAX High Efficiency includes double strength LoE 70/36 glass (70% visible light and 0.36 SHGC) with Argon gas is designed for northern climates with increased heating requirements. Meets ENERGY STAR requirements for North and North Central Zones.

TMAX SC™ - TMAX Solar Control includes double strength High Performance LoE 55/27 glass (55% visible light and 0.27 SHGC) and is designed for southern climates with significant cooling and glare-reduction requirements. Meets ENERGY STAR requirements for South and South Central Zones.

TMAX ALL ZONE™ - TMAX All Zone includes Triple Coated LoE 66/27 glass (66% visible light and 0.27 SHGC) and delivers the ideal balance of solar control and high visibility. It blocks 95% of the sun's damaging ultraviolet rays and meets ENERGY STAR requirements for All Zones.

What are the minimum egress sizes for MI EnergyCore windows?

Tue, 26 Jul 2011 14:21:00 GMT

The minimum RO egress sizing for the MI EnergyCore products are:

Double Hung: 3/0 x 6/0
Single Hung: 3/0 x 5/6
XO Slider: 4/6 x 4/0
XOX Slider: 8/0 x 4/0 with our standard 26” wide sash
Casement: 2/6 x 4/0

Here's some things to keep in mind:

In one or two family dwellings, Section R310.1 of the International Residential Code requires basements, habitable attics and every sleeping room shall have at least one operable emergency escape and rescue opening.

Where basements contain one or more sleeping rooms, emergency egress and rescue openings shall be required in each sleeping room.

Egress/escape openings may be provided by a window or a door.

Egress/escape openings shall open directly into a public way, or to a yard or court that opens to a public way.

All emergency escape/rescue openings shall have a minimum net clear opening of 5.7 square feet, except grade floor openings shall have a minimum net clear opening of 5 square feet.

The sill height shall not be greater than 44" off the floor.

The minimum net clear opening height shall be 24" and the minimum net clear opening width shall be 20". The minimum net openings shall be obtained by the normal operation of the emergency escape and rescue opening from the inside.

Emergency escape/rescue opening shall be operational from the inside of the room without the use of keys, tools or special knowledge.

Why does condensation occur on the inside of my windows?

Tue, 26 Jul 2011 16:14:00 GMT

This is a common problem in cold climates during the winter, when windows can be some of the coolest surfaces in the home. Condensation will typically appear there before it appears on other surfaces. Condensation is less likely to occur on interior walls, because they are typically warmer than "dew point."

The "dew point" is the temperature at which condensation will occur for a given humidity level.

To reduce or eliminate excessive condensation, the humidity level must be decreased and/or the ventilation increased

You can removed the amount of moisture in the air of your home by using a household demhumidifier or increasing the amount of ventilation.

Before investing in a dehumidifier or an HRV, check the structure for other possible moisture sources. Ensure the appropriate insulation and moisture barriers are installed in the attic, basement or crawlspace. Check for seepage in the basement.