heating and cooling for your house

heating_cooling

The available array of options for heating and cooling your house is significantly larger than it was just a few years ago.  Heightened awareness of energy efficiency and new, related techologies, have given us options that not only provide a much greater degree of thermal comfort, but do so at less cost and most importantly provide the homeowner with monitoring tools to increase awareness of how these systems can be optimized.

The tried and true (and not so efficient):  forced air systems.

These systems are really centered around their ductwork.  Of course there is a furnace and air handler or fan, to push the hot or cold air around the house.

Pros:  This system uses the same air handler to push both the cooling and heating requirements around the house in the same ducts.  This greatly decreases the cost of  the system and this lower cost is what makes these systems the default solution for most houses.  And all the floor-mounted grilles are a great place for losing stuff.

Cons:  maybe too many to list.  There is draftiness with all the air blowing around and the noise of fans and heat exchangers cycling on and off.  Multi-speed fans and zoned ductwork greatly increase the efficiency of these systems but come with often considerable cost increases.  The ductwork running around the house has to be coordinated with the structure to avoid too many unsightly dropped soffits all over the house and the proper sealing of ducts is critical to maintaining the systems functionality.

The luxe (but with some complications):  radiant heating

Hydronic radiant heat and fresh air systems with something for cooling (see cooling systems below) are quite nice and deliver heat to the lower half of the room via the floor, where most activity occurs.  The system combines a boiler, usually gas-fired, and an extensive system of plastic tubing embedded in the floor to heat up the floor surface.  This heating is greatly enhanced if the floor's mass is increased by encapsulating the tubing in a bed of concrete.

Pros:  the system is quite efficient and perfectly quiet.  It retains its heat well and nothing feels quite so nice on a cold day as warm floors.  The system of tubing can be zoned without too much trouble.

Cons:  the initial installation cost, especially with the concrete subflooring, can be considerable. Accommodation has to be made for small manifolds that usually mount in wall cavities with access panels for each zone.  The overall system can be slow to heat up and cool down depending on the thermal mass of the flooring system.  The performance of the system is also a bit dependent on floor surfaces and finishes.  And of course this is a heating-only solution to the HVAC problem.

The alternatives:

1.  air source heat pumps - inexpensive and a bit loud, they are good for moderate climates, not so good when temperatures drop below 40 degrees F.

2.  ground source heat pumps - not dependent on outside air temperature, but relatively expensive to install and often slow to respond to changing temperatures.

3.  solar panels - hydronic and photovoltaic - these are really energy systems not truly HVAC equipment, but their use along with radiant flooring or other systems can greatly reduce purchased energy usage.  These vary widely in costs with changing rebate programs and can have significant visual impacts.  And of course to be efficient you need to have good year-round solar gain.

4.  evaporative cooling - in low humidity areas, simply blowing air over water and into the house will drop interior air temperatures.  They are very inexpensive and provide a steady stream of fresh air into the house and are very energy efficient.  However, they need to be properly placed, usually high up on a building (for the cooler, denser air to fall in the house) and have significant visual impact.  And, obviously on days when the humidity might spike up, these systems may hardly work at all.  A fairly good cooling-only option in Colorado.

5.  wood and pellet stoves - Clearly these have become more efficient with the recent introduction of catalytic converters to reduce pollution and quiet fans to distribute heat.  However, they are usually single location devices and do not distribute their heat evenly around a house.  They are also take up space and need more constant attention for fueling, including the associated mess of pellets and wood.

6.  ceiling mounted electric radiant panels - this is basically electric resistant heating and works the same as the electric baseboard listed next.  However, these panels are ceiling mounted and do not pose the same furniture placement issues as baseboard heaters do.  Another advantage of these panels is that they can be easily zoned so that each room can be efficiently and individually heated.  However, as most electricity is still produced by coal-burning plants, they efficiency of these panels is greatly compromised.  And, of course, this is a heating-only solution.

7.  baseboard heating - hydronic and electric - these can be relatively inexpensive and easily zoned but as they run around the room typically create problems with placing furniture.  Recessing them in the wall makes for a very clean installation but may compromise the amount of wall insulation.  Of course, like the radiant panels above, they are a heating-only solution.

8.  passive solar heating - If you live someplace with sunny but cold winters it certainly would be dumb not to take advantage of some of that winter solar gain.  How much you do so may be very dependent on your house's orientation and views.  At the simplest, the use of passive solar techniques can provide summer shading of windows which allows winter sun to heat floors and walls and decreases the heating load required of other systems.  Very aggressive use of passive solar means creating thermal mass inside the house to absorb heat during the day and then release it at night.  These are "systems" that require some interaction with the homeowners to open and close windows and ducts and at their most efficient drive the basic form and shape of the house into a solar machine rather than a home.

9.  natural cooling techniques -  this is really a series of techniques and design considerations that can be combined to greatly reduce or eliminate the need for energy-input cooling for your house.  They do not work for all houses in all locations and, like passive heating, can begin to determine the physical shape of the house.  At a minimum, natural cooling lets in cool air at the bottom of the house and evacuates it at the top with either passive cooling towers or whole house fans.  The key to all these techniques is good air circulation throughout the house and the ability to move hot air out of the house. And, like the passive solar solutions above, these techniques usually require the active, daily participation of the homeowner - opening and closing vents and window and transoms - to operate the system.

The Big Problem

The nasty secret about all these methods is that calculating precisely the potential energy use of the building for heating and cooling is notoriously difficult.  Much of this stems from the base assumptions of the calculations and the use of degree days.  Degree days are the historical number of days when a building will need either heating or cooling multiplied by the difference between the outdoor air temperature and the ideal indoor air temperature (usually 65 degrees F).  It does not take into consideration the level of relative humidity on comfort nor the solar gain inside the house from the sun.  Obviously with our conditions in Colorado these two omissions are a major problem.  But what is worse is that the historic degree day data that is relied on by design professionals does not take into consideration a very common climate condition in Colorado - warm days that may need air conditioning coupled with cool nights that may need heating.  The degree day takes the average high and low for the day and compares it to the ideal temperature and assumes that difference for a full 24-hour period.  This greatly underestimates either potential heating or cooling loads required for a building to maintain the indoor ideal temperature.

This inherent flaw in the degree day methodology does not mean that every energy design professional's recommendations are void, but it does mean that a lot more work has to go into the design of a given building than might be otherwise needed for other areas of the country.  In the past, the most common flaw associated with HVAC design for houses we have worked on has been the under-calculation of solar gain within the house.  This has occasionally come from the lack of window shading - an architectural problem.  However, due the desire of a client to have a certain view, predominantly western views, no amount of window shading via overhangs will suffice to cut out all late afternoon direct summer solar gain.  Only adequate cooling methods will help overcome this intense solar gain.  These may be any of those listed above, but they will be needed for short periods of time and the beauty and drama of large panes of glass capturing spectacular views must be offset aggressively or the heat build up over the course of the summer will drive the indoor temperature gradually and inescapably upward.

Some Recommendations:

The first is to recognize that knowledge is power and that you should not skimp on purchasing good monitoring and control equipment.  I don't mean that you have to have expensive computer programs with sensor modules, but certainly a 24-hour, 7-day, multi-event programmable thermostat is an absolute necessity.  These are less than 50 bucks and will go a long way to help you customize your heating and cooling based on occupancy and will certainly save money on energy bills.  A step up from this would be to install a real-time electrical usage monitor which will show you your energy usage of your HVAC system along with all the other sources of electrical usage in the house.  Multiple studies have shown that just knowing what and how you are using energy will change behavior and save energy.

So, what to do about choosing an HVAC system?  This is an impossible question to answer in general and depends very much on the type of building, its orientation, energy costs, and perceived comfort level.  A good architect ought to walk you through these options and the many other systems and hybrids available.  Ideally a mechanical engineer is brought in to figure out the costs/benefits of each of these systems for your application.  However, as this is often prohibitively expensive, a well-qualified installer may be able to be a good team member along with the architect and a HERS rater to help you to determine the best approach for your house.

by Boulder architects M. Gerwing Architects

warmer climes

sky and sea

As the weather in Colorado is heading toward more much-needed snow, I am longing a bit for the sun and warmth of warmer climes.

These photos were taken by me over the holidays in the Florida Keys.  The Keys are a stringy set of islands connected by the Overseas Highway, like so many necklace beads.  Each island is just barely over sea level and the buildings are predominantly one- and two-story piles.  Consequently it is a landscape dominated by the horizontal layers of sea and sky.

wall

You might imagine that this would inspire similarly horizontal architecture, not just low and single-story stuff, but an architecture that celebrates the horizontal planes like the Prairie School work in the Midwest.  Alas, quality architecture has not really arrived in the Keys.  With the exception of the older parts of Key West, the built environment is uniformly cheap and composed largely of inexpensive variations of painted concrete block.

sea and sky

I'm sure there are architects and property owners down there trying to up the game a bit, but it will be a long task.  Unlike the almost limitless prairie, the potential of building down in the Keys would inevitably face the pressures of expensive and scarce land to build upon.  The dueling pressures of a relentless horizontality of the landscape and the efficiency of vertical building would be a rich conflict from which a quality architecture could grow forth.  As the old cliche' goes, difficult sites make for good architecture.

photos by Boulder architects M. Gerwing Architects

renovations - habitual patterns of use, by Boulder architects M. Gerwing Architects

We work on a lot of smaller projects that largely entail the internal reorganization of an existing house.  Most often these are houses that were built in the 1960's and the current homeowners are struggling with small, awkward kitchens and houses that are more formally arranged than currently lifestyles are well suited. New houses and restaurants are projects that allow for the most creative freedom, but it is these difficult spatial re-ordering projects that pose the greatest challenges and result in our greatest satisfaction.  Most of these projects are hemmed in with zoning constraints and building restrictions, but the single largest constraint is often in the minds of our clients.  Very often they have lived in the house for a number of years and although they are frustrated with it, it is very difficult for them to conceive of moving a critical function like the kitchen from one space to another.  They have developed habitual patterns of use that make seeing the forest through the trees extraordinarily difficult.

BL angled front

I found this to be true in my own home renovation.  Even as an architect, while living in the house it was difficult to imagine such a radical notion of demolishing and moving a kitchen across the house.  Sitting with the drawings in front of me it was clearly the right move to make, but standing in the house it seemed daunting.  And not just because of the associated cost and complexity that such a move would add to an already trying project, but because I had frankly become so used to getting my coffee and cooking so many meals there.

It is our habit that whenever we are faced with this kind of project we always run through a few exercises that test the possibilities of just these kinds of moves.  What if the dining room flipped positions with the living room?  How about if the entrance was on the other side of the house?  Or, as in a recent project, what if the kitchen moved into the master bedroom?

BL pres before and after plan

I make it a practice not to talk about the potential changes to a house when I visit the property for the first time.  For myself, it is the space and distance created while working in the studio that will most likely generate the most interesting solutions to a project, not walking around the house.  It seems a bit counterintuitive, but going to the actual site often makes the possibilities of a project less real, the potential of a project diminishes with the distance to the actual building.

In the end, it is a balanced attack on a project that provides the best answers and brings up the most interesting questions.  As an architect, you have to go to the building and study it, but you also have to go to your studio and take it apart in your head.  Architecture is practiced in the real world of walls and floors and dense materials, but it is best conceived in the imagination with paper and pencil, cardboard and glue.

by Boulder architects M. Gerwing Architects

Preservation of the Recent Past, by Boulder architects M. Gerwing Architects

Why do we preserve buildings? Why do we care about mute constructions, often old and unused, occasionally in the way or overlooked? We have all walked through great neighborhoods and parts of cities with magnificent old buildings and very few of us would show no concern at all if these places were simply ground down under the wheels of progress.  That doesn't mean we save every shack or old shed, but rather we recognize some value in mere continued existence of some portions of our collective past.  What is valuable about these old buildings is not necessarily what they look like or how they function, but what they are.  The preservation of some older buildings reminds us of what we are by holding on to some portion of who we have been.

Lloyd Wright_Scott Jarson

All well enough said, but when the desire to preserve runs head long into private property rights, what is to be done?  And when the object of preservation is a building not very old, maybe not even as "old" as any one of us, then how do we view the cause for preservation.

Most folks don't readily appreciate the architecture of the recent past.  It seems a bit naive and slightly embarrassing, like looking at yourself in old high school yearbooks.  Any building that we can remember when it was new can not possibly be of a value akin to the great Architecture of past ages. And yet so many of us can lament the loss of truly great buildings, like Penn Station, that most of an earlier generation held in similar contempt that we place so many buildings constructed in the 1950's and 60's.

cyclorama2_Wikipedia Commons

The buildings shown here aren't some obscure shacks threatened with demolition.  These are significant works by some of the greatest architects of a generation ago - Bertrand Goldberg, Richard Neutra, and Frank Lloyd Wright.  You might not like these buildings, but that is not the point. For God's sake, most communities in the US have fashioned a minor economic industry centered on tourism to Wright houses, not the financial benefits of their destruction.

Prentice_Landmarks Illinois

It is disheartening to sit here in 2013, with over 50 years of preservation battles - successes and failures - behind us only to realize that years from now I will have to explain to my daughters why my generation tore down Neutra and Wright buildings.

The case to save Neutra's Cyclorama Building, Goldberg's Prentice Hospital and Wright's Lloyd Wright house can all be linked to here.

by Boulder architects M. Gerwing Architects

Regional architecture - Florida Keys, by Boulder architects M. Gerwing Architects

Keys5

I have often written about my interest in regionally specific architecture, especially vernacular forms that derive from local climatic conditions or materials availability.  I recently spent some time in the Florida Keys and in my typically geeky architecture fashion, spent almost as much time looking at the local historic buildings as I did relaxing on the beach.

Keys4

Like any relatively isolated region, the architecture of the Keys, and especially Key West, is dominated by its largest growth period, starting with the late Victorian era and extending to the Depression.  As a result, the typologies of houses you find are almost exclusively wood-framed, simply-gabled homes with painted lap siding and more-or-less overly wrought scroll details.  While there are plenty of houses from other periods, these basic vernacular houses became the standard that has been replicated, often less successfully.  The funky mid-century commercial architecture of the Keys, including the building-as-sign googly constructions date from the 1950's and 60's when the Overseas Highway surplanted the train and boat as the dominant mode of access to the Keys, are more often found at the beginning of the island chain, closer to Key Largo.

Keys1

As in so many older sea-faring communities, the predominance of horizontal wood siding reminds one of the hulls of boats and the gable-fronted houses resemble so many upturned boats.  Of particular interest to me are the use of shutters and porches to mitigate the harsh Caribbean sun while still allowing ample breezes to move through the structures.  Unlike Italian house shutters, the Keys shutters are plantation style, often not individually operable but top-hung as a panel that can kick out at the bottom.

Keys2

Of course here in the Keys, the shutters do not just provide sun control, but are necessary protections for the Gulf storms and occasional hurricane.  For that reason they can be found on doors and windows within porches, well beyond the areas where sun shading would be necessary.  These shutters provide a kind of vertical emphasis to the buildings that contrasts with the predominant horizontal siding and decorative rails.  The overall effect is of a lightly sprung craft, held in tension, that takes the kind of maintenance and attention that only a boat-owner could appreciate.

Keys3

The older portions of Key West are also fairly urban and dense, with house fronts mere steps from public sidewalks.  The shutters are also used to create privacy while keeping doors and windows open.  As in the photo above, the subtle delineation of public and private spaces, from sidewalk to private walk to porch to interior, works in about ten feet of space, each layer carefully playing its role.

This kind of attention to the details of public and private space are often lumped into the concepts of New Urbanism.  But, as you can see, some good old fashioned urbanism is successfully at work, design solutions worked out over years of lived experience that architects would do well to study. And shutters that actually work, not just applique patterns, a fearful architect's pet peeve.

by Boulder architects M. Gerwing Architects