Technology, it seems, has given us the opportunity to defy nature’s impact on our lives in all but the most extreme conditions. This is particularly true within the confines of our houses and other buildings. In our homes, the words “climate control” no longer suggest the nefarious plan of a volcano-dwelling, Bond villain, but rather an expected level of modern comfort. Our HVAC systems are powerful enough to swing our homes from sauna to tundra regardless of the conditions. We can lay around in our favorite shorts in the middle of January and slip into a comfy sweater in August. But, what is the cost of this “comfort”? How much control do we really need?

One of the challenges of building energy efficient homes in the US is the idea that the occupant needs god-like control over their interior environment. This often means over-sizing a system to the point where it can massively overpower the influence of the most rare and extreme weather conditions. As one might expects, this sort of sizing has several major drawbacks:

Cost
This is probably the least surprising drawback of an over-sized HVAC system, but it is a particularly glaring problem in homes where serious investment has been made in insulation and air sealing. All that cash that was dumped into sealing up the house should pay back immediately by reducing the HVAC load and thus the size and cost of the HVAC system. Over-sizing your heat and air-conditioning systems simply negates that savings.

Efficiency
Huge gains have been made in HVAC efficiency over the years, but many of those gains are negated by over-sizing. Efficiency ratings on the best HVAC systems are high because when sized correctly there is little cycling loss. This means that the system isn’t constantly turning on and off which uses a lot of energy. HVAC systems are much more efficient when running for longer cycles, a condition that won’t occur if your system is over-sized. This may seem counter-intuitive but if your neighbors’ AC is running less than yours, they are probably spending more on electricity (unless of course they simply don’t mind sweating).

Humidity
Short cycle times also hurt an HVAC system’s ability to regulate humidity which can lead to condensation and mold, especially in particularly damp climates. It is much better to have your AC running constantly at an efficient level than to have it blasting for a few minutes and shutting down, particularly if it is helping regulate humidity.

Comfort
That cycling issue rears its head again when it comes to the comfort of occupants. Even a well insulated home tends to lose it’s heat at exterior walls, windows and doors. With a centrally located thermostat the quick blasts of heat that warm the center of the house may come too late or too infrequently to help the extremities. A short cycling HVAC system is like wearing a vest when the weather calls for a coat, everything outside the core is uncomfortable.

There are a variety of other reasons people might give to disparage the over-sized HVAC system including increased noise and the physical size of the thing, but I think you get the basic idea . . . over-sizing is bad. So, why is it done? If we know it is less efficient, less comfortable and more expensive, why is it such an ongoing problem?

The answer lies in the first two paragraphs of this post. People want control. Regardless of the outside conditions, there is this idea that one’s chosen house temperature is an inalienable right. If we want it to be 78 degrees in our home all the time, we expect out HVAC systems to make it so. A right-sized system might not be so compliant, particularly on those days of rare extremes.

Does this mean the occupants are destined for discomfort? Of course not. The vast majority of days temperature control will be as flexible as you could want, but on those aberrant extremes there may be some limitations imposed. One might need to settle for 68 and a long sleeve shirt on a sub-zero day in Philadelphia. In Maine, one might need to turn on a fan and wear a pair of shorts when the temp tops 90. Generally, a right-sized system expects one to behave (and dress) slightly more seasonally, but the overall effect will actually be more consistent throughout the home and thus, more comfortable.

So, what is your ideal indoor temperature? How much fluctuation would you be willing to allow the seasons to impose on you? Did I miss anything important about HVAC sizing?

Give us your thoughts, opinions and expertise in the comments.

We thought it would be a good idea to review our new ventilation strategy and design implemented in the recent Passive Project. The ventilation strategy in the 100K House was different than most typical houses and the Passive Project took things a step further. We’ll start with the outline:

1. Use a very efficient mechanical ventilation system (ERV or HRV >90% efficient)
2. Design an efficient duct run layout to maximize efficiency of your ventilation system
3. Eliminate all dedicated local exhaust systems ducted directly outside
4. Eliminate all dedicated appliance exhausts that are ducted directly outside

High Efficiency Mechanical Ventilation (ERV or HRV)

The Passive House standard requires that you install a ventilation system with > 75% efficiency and a low electric consumption of 0.45 Wh/m3. When we say ventilation system, we are talking about either a Heat Recovery Ventilator (HRV) or Energy Recovery Ventilator (ERV). HRV’s exchange heat only while ERV’s exchange both heat and humidity.

A 75% efficient unit will be exchanging 75% of the heat from the indoor air with the cold air coming inside. The closer that figure is to 100%, the closer the fresh, incoming air will be to the existing indoor temperature. Efficient electrical consumption is basically referring to the type of motor used in the ventilator. European models typically are using the most efficient DC motors available, while unit made in the US will suck a bit more power.

If you are shopping the globe, you have a couple of options for mechanical ventilation that meet the Passive House reqs. If you want to buy in the US, you have one choice – The UltimateAir RecoupAerator.  This bad boy comes in black, runs at 95% efficiency and sucks a paltry 40 Watts while delivering 70 cfm to your home (250W @ 200cfm). This is what we spec’ed on 100K and continue to use in Passive and for all foreseeable projects in the future. We set it on its lowest setting which usually measures about 60cfm in each room vent and let it run 24/7/365. Simple.

This unit also comes standard with a MERV 12 filter which gains us LEED points and keeps our client’s air very clean. Lastly, it features an “EconoCool” feature that can be used during the summer to reduce cooling loads. Flick this switch on and the unit will recognize when the temp drops below 65 degrees F and automatically shut off the energy recovery and begin swooshing that cool night air directly into your bedroom.

Maximize Efficiency with a Well Designed Duct Layout

Now that we’ve got the correct ERV for our needs, we need to pay attention to how we run our ductwork to maximize efficiency. The ERV will suck out stale air from the home and deliver fresh air to rooms at the same time. Below is how our PHIUS consultants recommended that we locate our suckers and blowers (technical Postgreen terms):

Stale Air Exhausts (Suckers)

• Bathrooms
• Kitchen
• Near Washer/Dryer

Fresh Air Inlets (Blowers)

• Bedrooms
• Living Room

Now we don’t just want to throw the ductwork in any old pattern to get to these rooms. We want to minimize 90′s and have straight runs as much as possible. Basically a 90 degree turn is equivalent in resistance to airflow as 25′ of straight duct and a 90 degree register termination can add as much as 80′ to your calcs. The main pointers given by both PHIUS and the manufacturer of the UltimatAir are as follows:

1. Keep it SHORT
2. Keep it STRAIGHT
3. Keep it SMOOTH
4. Test after the system is commissioned

The diagram above is a 3D layout of our proposed duct runs for the Skinny Project. Laying these out in Sketchup is pretty quick and helps us really think about how each duct run needs to get to it’s final destination with the fewest turns. As a result of this exercise we added another small chase wall next to one of the closets in an upstairs bedroom. This chase will not be seen, and could be considered a minor detail, but it will greatly improve our duct efficiency and reduce labor time for our installers.

Other tips given to us for optimal ERV system performance:

1. Always use smooth, hard duct and avoid flexible duct as much as possible.
2. Insulate the two lengths of duct running between the exterior and the ERV. This will prevent condensation from forming on these lengths of ducts.
3. If noise is a concern, add one 3′ section of insulated flex duct to the supply side of the ERV. Install this section as straight as possible and it will act as a silencer without needed to buy an expensive silencing duct section.

Eliminate Dedicated Local Exhaust

The big difference between the 100K and Passive ventilation strategies was increasing the amount of intakes/exhausts inside and eliminating the local exhausts in the bathroom and kitchen. PHIUS highly recommends doing away with any local exhaust that is basically sucking conditioned air directly out of the homes and replacing it with whatever outdoor air can be sucked through any cracks in your envelope. Eliminating the local exhausts also reduces your exterior penetrations through the envelope by at least two (more if you have more than one bathroom).

To compensate for the lack of dedicated local exhausts, we install suckers in the bathrooms and kitchen. On top of that, we throw an ERV boost switch in each of these rooms so that occupants can boost the ERV fan to max setting (around 200 cfm for UltimateAir) while they are in use. These switches are also useful for parties or times when a lot of CO2 producing bodies are inhabiting your space.

In the future we plan to take this boost switch a step further by linking it directly to the bath lights with an auto shutoff delay. Basically when you turn on your bath light, the ERV will automatically boost to high. When you leave the bath and turn off the light, the ERV will remain on boost for another 10-20 minutes to fully clear out any fumes you may have generated during your visit. This gets us a LEED point also.

Eliminate Exhausts for All Appliances

This is less of a ventilation system design aspect and more of a whole house envelope and mechanical design strategy, but I like to include it here as well for good measure. By using electric water heating backup for our solar thermal and a condensing dryer that does not require venting, we have eliminated all appliance ducting to the outside. Less thermal bridging and warm air being sucked out of our homes. To compensate, we locate a sucker near the condensing dryer that can tend to get a little steamy at times. In the future designs, the washer/dryer is moved into the bathroom to allow the bath sucker to serve two functions.

That’s it. I hope this helps with any mechanical designs you may be considering for your next green building project. Comments are below.

One last note:
One question we still get a lot is if our homes are too tight and cause indoor air quality problems or pressure balance issues that would cause the windows and doors difficulty in opening and closing. This is a bit of an outdated concern from when production builders first started making their homes tighter without adding mechanical ventilation. Now, this issue is a thing of the past unless you have a very poor builder…

We have been planning on using a supplemental split-ductless or heat-pump HVAC system in the 120K House from day one. These units are very efficient, supply both heating and cooling, and eliminate ductwork that can further reduce efficiency and air quality in standard HVAC systems. The main complaint I have with these units is that they mount to the wall and come in non-design savy “white-box” configurations.

If only someone would solve this simple industrial design issue and make an attractive wall-mount unit. Well, along came LG and did just that with their ARTCOOL series of split-ductless units. First off, these LG units are typically slimmer with cleaner lines than the average unit on the market. Secondly, they come in a variety of finishes including Mirror (SS), Wood Grain and even picture frame units that can hold a picture of your own in it.

VS.

Above, you can see a comparison between a normal Fujitsu model that we originally spec’ed out and an example of the LG Mirrored unit that we are now looking to use. This is a slight upgrade that was not in the original budget, but I think it will be well worth it considering the typical client of ours will most likely be more design savvy than the average home buyer.

A version of the model pictured above will be going in the 120K House shortly and we will have more updates and actual photos once it is installed. On another note, it’s nice to see companies like LG placing importance on the field of Industrial Design. So many companies seem to pass this part of the company off as to artsy to be important to their brand or bottom line. This seems short-sighted and just plain outdated. More and more companies every day seem to be catching on and blessing us with more beautiful products at the same or similar cost. Thank you LG and everyone like you.

Problem Statement

The high efficiency Munchkin gas boiler is more expensive to install (>$3,500) than budgeted as both a backup to the Schuco Slimline II-80 solar thermal system spec’ed out for domestic hot water and a sole source of heat to our hydronic radiant heating system (more on these mechanicals here). Installing gas service to the house will also cost an additional $2,000 in permitting fees and additional plumbing costs to run the line inside the house. The high efficiency (97%) of the gas boiler is needed to accomplish a HERS rating of 52 that enables the 100K House to achieve a LEED Platinum rating. Electric alternatives to heating water are not nearly as efficient overall and will dramatically increase our HERS score.

Hypothesis

If we increase our solar thermal system parameters by two more 25 square foot solar panels and an additional 80 gallon storage tank with integrated electric backup heater, we will be able to eliminate the gas boiler while reaching the same efficiency as the gas boiler backup design without increasing overall cost. This design has the potential to be lower in overall cost with the eliminating of any gas service run to the homes at all.

Key Variables

The big hurdle in switching to all electric water heating while still achieving the same HERS rating is the difference in the source to site multiplier between gas and electric. What the heck does this mean? Basically, since the US is so lousy at efficiently generating and transporting electric power to our homes, the HERS rating system multiplies the power used by electric appliances by 3.16 to compensate for the roughly 30% efficiency level we are generating electric at currently. For gas, this multiplier is only 1.02. So, if we are going to replace our gas boiler with an electric backup, we must be three times as efficient in terms of total power used.

We have calculated that we will need to compensate for roughly 67% of our radiant heating demand in the winter with increased capacity in our solar thermal system. This leaves us with just over 2,000 kWh’s of supplementary electric backup heat for the entire year.

Yesterday a three man team from local solar experts, Solaris Energy, sat down with us for a marathon meeting to try and determine if our goals above are possible. We have a proposed design and will be sending it off shortly to the fine engineers at Schuco to see if we are in the ballpark or totally off base. Stay tuned for the update and lots more math.

Today’s Marker Time is the first in a series of videos that will look at the Energy Efficiency of the 100K House project. The first in this series looks at the utility costs of the 120K House versus that of a similar new construction house built to code and an existing house that is not new. This video is a bit heavy on the numbers and was filmed late in the day when my enthusiasm levels were a bit drained, but hopefully our points come across fairly clearly.

Here is a recap on some of the numbers covered in the video:

• The 120K House uses half the energy of a standard code built home
• An existing (non new construction) home uses 2.5 times more energy than the 120K House
• A code home will cost an extra $1,037/year or $86/mo compared to the 120K House
• The extra utility cost of the code home raises the actual cost of a $250K purchase price to $263K
• An existing home will cost an extra $2,034/year or $170/mo compared to the 120K House
• The extra utility cost of the code home raises the actual cost of a $250K purchase price to $276K
• If you applied the extra $170/mo to the mortgage on the 120K House that you would be saving in utility costs

The second “Marker Time” video covers Indoor Air Quality in a bit more detail. Today we take a look at mechanical ventilation inside the very tight envelope of the 120K House. We cover both local (kitchen & bath) ventilation as well as whole house ventilation in the form of HRV’s (Heat Recovery Ventilator) and ERV’s (Energy Recovery Ventilator).

The task of figuring out exactly what we are going to do for kitchen ventilation has been on the back burner for some time. As ground breaking is getting closer, this needs to be nailed down. Here are our criteria for the kitchen or cooktop ventilation:

• Exhaust flow rate that accomplishes 5 kitchen air changes per hour (LEED req) or 400-500 cfm.
• Energy efficient operation
• Quiet operation
• Slim/modern design
• Cost effective

Meeting all of these criteria on a budget is no easy task since most decent looking stainless steel range hoods range from $500 – $1,000 and tend to be ineffective and noisy. If we didn’t have the quiet criteria things would be a lot easier, but quiet has been on the list for some time in my head for a couple of reasons. For starters, a quiet range hood is perceived as a higher-end feature in a kitchen that the majority of developers ignore altogether. Secondly, I have observed many not using their range hoods at all. When asked why, they say that it is too loud and drowns out conversation during cooking or bothers others in a nearby room. What good is adequate ventilation built to LEED standards if people don’t use it due to the noise?

OK, back to our research. At first seach it was not clear what the alternatives were to the traditional designer range hood that would fit our modern aesthetic. Luckily I found an HVAC site with a thorough description of kitchen ventilation systems and all of the components that go into a quietly operating system.

After reviewing the site above it is clear that the components we need to meet all of our criteria are as follows:

1. A built-in hood liner with washable grilles and sometimes lights
2. ductwork
3. An inline or roof mounted fan
4. A backdraft damper to keep outside air leaking through the ductwork when not in operation
5. A silencer to quiet the metal ductwork

This sounds like a complex and expensive system at first glance but it appears that if the components are chosen carefully, the total cost will run about $500. While not cheap, the quality and effectiveness will far surpass the standard range hoods on the market.

One of the options I liked most at HVACquick.com were their Dayus Filter Grilles that could be mounted flush with the ceiling above an island cooktop like we have. This would maintain an open ground floor with unobstructed views from the living room to the back doors for less than $60. This is a bargain compared to some of the hood liners that start at $500 and would be a prominent fixture on the ground floor.

Next time I’ll try to spec out the exact components and prices of each to be used in the 100K House.

Two weeks ago we looked at two solar thermal and radiant heating systems by Radiantec. One of the options that Radiantec offers is a very simple diverter valve that allows the homeowner to run the incoming cold water through the radiant floor prior to reaching the hot water heater and fixtures. The diagram below details this setup that advertises free additional cooling in the summer for homes with radiant slabs such as ours.

I’ve had some discussions about this theory with some professionals in the past two weeks and thought we might benefit from a closer look at this setup. First, Radiantec offers test data based on a case study house they built in the 80′s in a DOE Report (pdf). The cooling option is discussed on pages 22-23.

Radiantec Test Case Data & Assumptions

• 2 story, 1,400 sf home with a 720 sf 5.5″ thick concrete slab on grade foundation
• Water supply temperature of 55 degrees and a design temperature of 78 degrees
• Household water consumption of 300 gallons per day
• Heat exchange efficiency of 90% in the radiant slab
• 51,667 BTUs extracted per day

100K Adjusted Figures

• 2 story, 1,050 sf house with a 648 sf 5.5″ thick slab on grade foundation (0.9 Case Study)
• Household water consumption of 100 gallons per day (0.33 Case Study)
• 15,345 BTUs extracted per day (0.9 * 0.33 * 51,667)

OK great, but what does this mean. Well I dug up an estimated cooling requirement calculated by a mechanical contractor a few months ago that said we needed just over 22K BTUs of cooling. This was a previous version of the house that had less insulation, poorer windows, over double the lighting and took into account none of the passive cooling strategies. So if we used this old estimate, the free radiant cooling feature would cover 70% of our cooling requirements. I can’t quantify the effects of the passive elements on our cooling load to get a better figure without spending a lot of money on more energy modeling, so for now we’ll have to be happy with these figures.

OK this is all great, but what about the main concern with radiant cooling – condensation? Well the lovely people at Radiantec (I like them more and more as I delve deeper into their websites) have created an FAQ to address this issue and other questions on the cooling feature. They address the condensation issue in two parts:

1. Since the radiant tubing is embedded in the concrete and not exposed to the air, you will not get condensation on the tubing. Makes sense, but what about the slab itself?
2. They claim that the system will not create enough cooling to present a whole house moisture problem and go on to say that in very hot and humid climates an air conditioner will be needed and will help dehumidify the air.

This is nice but does not entirely quell my fears of a slimy floor syndrome in the summer. I happened to run into a Mechanical Engineer, Joe, from Bruce Brooks & Associates at a local pub last night and decided to get his thoughts on this issue. He has had some experience using radiant cooling in commercial applications, but like most cool HVAC techniques, it is not widely used in residential applications. I first thought that the fluid in radiant cooling systems would be cooled to a temperature much lower than the 55 degrees we have in our calculations but he said that it is actually only 48 degrees. This hurt my assumption that we would not get condensation due to the higher temperature of our cooling liquid.

Next I asked him if active dehumidification would help in the house as needed. He said it would but was unsure of what degree. Joe then mentioned that they actually simply create an air flow over the radiant cooling surface with fans. I mentioned that we will have multiples ceiling fans in the house and he said that would certainly help and might just be enough.

So in summary, I am now about 95% confident that our combined low-cost cooling and dehumidification techniques will be sufficient enough to keep the home comfortable on all but possibly the very hottest and longest heat waves of the summer. I especially love the fact that we can achieve up to 15K BTUs of free cooling daily but utilizing the radiant cooling detail from Radiantec.

Let us know below if you think any of this sounds crazy…

In our last post we spoke of a Shuco Slim Line solar thermal heating package that would be used in conjunction with a closed loop radiant loop and a high-efficiency gas boiler to heat the domestic hot water and the radiant loop as needed. This system uses the solar thermal system to preheat only the domestic hot water. The gas boiler then heats all of the radiant system while also acting as a backup for the domestic hot water.

An alternate system is one in which the solar thermal system can heat both the domestic hot water and the radiant loop. A Vermont company, Radiantec, offers two variations of their solar thermal and radiant heating systems that do a good job at handling both. I spoke with Don Vance at length last week about his systems and recommendations for our homes. Don is an extremely helpful guy and provided us a quote for both a radiant system and solar thermal system size specifically for our homes a few months ago.

Radiantec Solar Option I System

Option one uses the concrete slab as well as the earth below the slab to increase the solar energy storage area.

This option is unique in that it is a hybrid system that combines the best of active and passive solar thermal technologies without their respective disadvantages. Radiantec has one numerous awards for this design and has published a 28 page report for the US Dept of Energy (pdf) on their site detailing the benefits of this hybrid system over traditional setups.

While the website recommends up 7-8 solar collectors, Don sized our system at only 3 panels. This is due to our climate conditions, available solar energy and rough heating demand. We have a smaller home that is well insulated and located in a milder climate than Vermont. If we were to add more panels, we would have trouble handling the excess heat generated in the summer and would have diminishing returns on the system as a whole.

Some of the things I like about this system are that it improves the efficiency by utilizing a much larger mass for solar energy storage. This will mean that it will take the mass longer to heat up, but once it reaches the desired temperature, it will remain stable for a number of days without additional heating. Also, this setup has the ability to heat both domestic hot water and the radiant heating system. When the radiant heating system no longer requires additional heat, the system will automatically heat the domestic hot water supply instead.

This system is intriguing and seems to be more efficient than the current setup we are looking at. I still have a few questions about it that need to be resolved and of course there is cost as well.

Radiantec Solar Option II System

Option II from Radiantec is similar except that the radiant loop and domestic hot water are heated together in an open loop.

The key aspect that interested me about this setup was it’s ability to cool the home for free during the summer by running the cold water intake from the city through the slab prior to delivering it to it’s point of use. In the DOE report, Radiantec claims they are able to extract over 50K BTUs per day from a 2-story, 1,400 sf house with a 720 sf slab on the ground floor. Not bad for free cooling.

Both options have the ability to contribute to both domestic and radiant water heating, but if there was a way to combine the efficiencies of Option I with the ability to cool the home during the summer, it would seem like the best way to go for us.

Check out Radiantec’s solar site – www.radiantsolar.com – for a wealth of information and background on these systems.

We have been trying to nail down the mechanical systems to spec out in the house for some time now. We are getting very close, especially after the recommendations from the energy modeling. Our mechanical contractor is having health issues and had to bow out of the project so these may be subject to change based on recommendations of the ultimate mechanical contractor that comes in. We are also entertaining the option of just installing everything ourselves with the cooperation of a good plumber.

Solar Thermal System

SCHUCO Slim Line II-80 Solar Thermal Package – Currently we are looking at this two panel packaged system that comes complete with the storage tank with integrated heat exchanger. The price is not to bad at about $4K list from what I can find, but the important thing is that the entire package is certified by the Solar Rating and Certification Corporation (SRCC). This will qualify us for $2,000 federal tax credit that is available for solar thermal installs. The tax credit is for 30% of the installed cost of a qualified solar thermal system, so after labor it should be easy for us to qualify for the full amount.

Lastly, installing this system will take care of a majority of our hot water heating demand and will increase the overall efficiency of the house to the level that will allow us to take advantage of the full $2K federal tax credits for builders who build a home that achieves 50% energy savings for heating and cooling compared to code homes. These two tax credits will hopefully cover the majority of the solar thermal system and allow us to hit our energy efficiency targets on our budget.

Hot Water Gas Boiler

Munchkin T50-R2 Boiler - We were recommended a number of high-efficiency boilers but are leaning towards the Munchkin brand at the moment for the following reasons:

1. 95.1% efficient (AFUE %)
2. Affordable – Around $2,500 list where most others are above $3K
3. Modulates for improved efficiency
4. Great brand name

The above two items in our mechanical system will very efficiently handle both our domestic hot water needs as well as our radiant heating needs. The solar storage tank will supply the domestic HW only and use the solar thermal panels as a primary heat source and the boiler as the secondary heat source. The boiler will be connected to a closed loop radiant system as well as the solar storage tank.

Radiant Heat in Slab on Grade Foundation

We will be installing PEX tubing ourselves for the radiant system prior to pouring the concrete slab that will remain unfinished. We will purchase the rest of the components needed as a pre-assembled package from any number of vendors that offer them. Not much more to say about that.

Energy Recovery Ventilator (ERV)

It looks like we will be going with the Ultimate Air RecoupAerator Whole House ERV Unit (Model 200 DX). This model has a couple of advantages over others we’ve looked at:

1. As an ERV, it will maintain humidity as well as temperature, where an HRV only deals with temp
2. Very low power consumption and quiet operation
3. MERV 12 filter comes standard helping with LEED points and keeping the indoor air cleaner
4. 95% efficient
5. Variable speed controlled by time settings or programmable thermostat
6. EconoCool feature allows cooler night air to be brought in directly during cool summer nights to cool the home without traditional air conditioning.

This last point is obviously a big one for us. Our concrete slab should absorb a lot of heat during the day and then release it at night as the ERV cools the home with fresh outdoor air.

Options

There are a few options or variables that could cause this list to change. For one, there are quite a number of ways we could configure the combination of radiant, solar thermal and domestic hot water. I may go through a couple other possible options in the next few days. Besides the ERV, we may install some type of dehumidifier in the home to ensure that the summer months are comfortable. I am actually considering purchasing a room dehumidifier and running it in our poorly insulated loft apartment to see how it works. We will most likely have to make a decision prior to gaining any useful data from this experiment, but I think it will be valuable none the less.