Environmental Technology 2
Systems (Comfort, Climate Control,
Florida A&M University | School of Architecture
ARC 5662 | Spring 2005 | Walter Grondzik
Due: each Monday -- by 5:00 PM via e-mail
Context: This is an
on-going, semester long assignment that asks you -- at
the beginning of each week -- to reflect
Deliverables: Once a week (by 5:00 PM Monday) send an e-mail message to <email@example.com> that presents a concise reflection upon the previous week's course topics/materials. A reflection may be --
1. A specific question regarding some
concept or issue discussed in class or presented in the
2. A brief recounting of an observation
of some concept, issue, system, or component you came
across in your
3. A statement (or question) regarding
the applicability of some concept, issue, system, or
component to a design
Format: Submit each reflection
in the body of an e-mail message. If an image is to be
submitted as an enhancement
Discussion: Reflections will
remain anonymous -- once received. They can not be sent
anonymously, as no credit
The first "reflection" is due Monday 17
January. Unless otherwise noted, a reflection will be due
every week (except
Webster=s New Unabridged Dictionary
... and that's it.
Student reflections posted "as received" and without editing (and instructor responses)
I am interested in the HVAC system requirements for educational (K-12) and health care facilities (hospitals and nursing homes).
OK ... but a reflection with more connection to the current topics covered in class is expected as a response to this ongoing assignment.
I'm not quite sure if this is the type of reflection that you are looking for, however the first lecture sparked a couple questions. The first is more a of a request for further insight as the point brought up regarding the lack of a/c in residential units in the north as apposed to commercial structures. The second was regarding thermal delight, and how can one quantify this if at all possible?
The residential AC issue is essentially one of cost versus demand. Commercial buildings in almost all climates require mechanical air-conditioning. Residences, on the other hand, can often do without mechanical cooling (by using natural ventilation) for most of the time during a summer. Those who can afford it may decide that even a few days of summer discomfort is not acceptable and demand mechanical cooling. Most just gripe and wait for it to cool off. As the length of summer discomfort increases (not a few days, but a few weeks, a few months) demand for mechanical cooling increases -- and at some point and geographic locale becomes the norm.
It might be possible to quantify thermal delight with an appropriate research project -- but is it possible to quantify spatial delight or aesthetic delight? If not, are these not still worthy goals? The point being that much in architecture is hard to truly quantify -- much much can be predicted (if not explained) by observing patterns of people's responses.
From the reading: What are the mechanics of a thermal cooling tower? what are the optimum design conditions for its use?
We'll get to this question in a few weeks, as we look at cooling equipment.
Yesterday I had a personal experience of "thermal delight". Visiting Miami over the weekend, the weather was rainy, overcast, unattractive. Yesterday the front clear, the sky was clear blue and the sun shining. Walking down Ocean Drive I noticed the temperature to be in my personal perfect zone, about 70 degrees. The radiant warming from the sun was just enough to warm my face, and the tropical sea breeze was gentle but noticeable....ahhhh
I would like to make an observation on an issue of thermal comfort. Recently the weather outdoors got significantly cooler, prompting the use of heating systems indoors. I observed that in virtually all storey apartments i visited, there is a big temperature differential between the warmer upper level and a cooler lower level. This naturally occurs due to upward movement of warm air . Often the solution is introduction of electrical heaters at lower floors, which results in additional energy consumption. Why is such a situation not taken into account at the design stage of the project?
Because of costs (specifically first costs), most residential HVAC systems are single zone systems (one point of control) -- even though the buildings they are used in may really need 2 (or more) zones. First cost is such a powerful driver of consumer decisions that potential discomfort and/or additional energy use are usually discounted at the time of decision-making (design or purchase). It is essentially "this WILL cost $" versus "this MAY result in x."
I have a question on the fundamental value of achieving a sustainable design. How can achieving it make a difference? Most times the cost achieving a self-sustainable dwelling that provides comfort is extremely high.
This is the fundamental question that society and the design profession faces today. The first cost of sustainability may be quite high (relative to the alternative same-old, same-old); but the cost of unsustainable design is the demise of our current standard of living (if you accept projections about carrying capacity [ecological footprints] and fossil fuel reserves). If both alternatives were in the same time frame the question and choices would be easier to make -- but the additional cost is now and the results are in the future. We pay the costs, other get the rewards. This runs counter to the economic culture of most of the West and therefore is a hard sell.
The discussion on heat gain and loss was very interesting to me. I found it intriguing that I became more aware of slight and drastic changes in temperature.
This is probably good -- although I worry about the effect of our discussion of indoor air quality.
I wonder if churches know the importance of thermal comfort. I say this comment because I was sitting in church on Sunday and I felt like I was in hell. It was extremely hot and uncomfortable, which of course made everyone sleepy. I have never been to a church where the temperature was comfortable. It's always too hot or too cold. But then again thermal comfort is all a matter of opinion.
Churches are an interesting design problem. Many are unoccupied for the majority of the week -- and then are quickly filled by a high density of people. Larger and more sophisticated churches pre-condition their spaces. This is especially critical in the summer, when the systems often can not handle the huge occupant cooling loads that literally shoot from small to huge in a 15 minute period. Radiant condition become more important in a space that has on-off conditioning. If a church is heated only during services, during the winter interior surfaces (MRT) can be quite cool even though the air temperature is near comfort.
I enjoyed the conversation about heat gain and heat loss this week, but I wish that we had gone into more detail about recycling building materials which was covered in the reading for this week. Is there anyway that you could obtain more information on that for us?
This is an incomplete answer, but the question is huge and the data lacking. There is not a lot of good information readily available about embodied energy -- the energy content of building materials. Having said that, it is pretty obvious that if you use recycled materials you "save" whatever energy is embodied in the material. Likewise, using local materials reduces the embodied transportation energy connected to a material. Thus the focus on reuse and recycling of materials (and the use of local materials) in green building programs.
Reviewing some of last semesters lectures was helpful (conduction, radiation, convection, evaporation, etc.). However, I am still a bit confused over wet, and dry bulb temperatures. After doing the reading I understand how it is calculated through the use of a sling psychrometer, but not so sure where it is applicable.
This will be made clear during this week's lab (I hope). To use a psychrometric chart you need any two properties of the air; wet and dry bulb have historically been two easy to obtain properties.
Is there a significant difference in type of indoor air problems between the types of buildings? Like between single-family homes and apartments. Or residential to commercial? Seems like the standards for sick building syndrome are absolutely varied between developed and developing countries. You don't ever hear of indoor air related problems in developing countries, even though they use substandard materials extensively. For example they asbestos based ceiling boards are not only widely used, but are also hardly ever given protective coat of paint.
As a general rule, the tighter the building envelope the more like that IAQ problems may exist. Single-family residences tend to be a bit leakier than commercial buildings -- and also more envelope-dominated (most rooms in a house have an exterior wall exposure). There are stark differences between expectations for IAQ from country to country. IAQ problems are in many cases not immediately life-threatening and as such may not be on the list of items of most concern in a developing country. In addition, poor construction practices lead to leaky buildings that are well ventilated (or infiltrated) -- lessening the incidence of IAQ issues. IAQ was not a problem in most US building types until construction tightness improved in response to demands for energy efficiency.
I have two questions for this week. A friend of mine works in an office with no exhaust system and I know that this affects indoor air quality. Right now, the majority of the employees are coming down with the flu. What would be an economical way to add an exhaust system to this fairly old building to improve the air quality? My second question is how does the blizzard that dumps two feet of snow in 24 hours affect the indoor air quality.
The blizzard is the easy question. Unless the snow block air intakes (not unheard of), there should be no real impact on IAQ. The only way to answer the first question is in the context of the specific building. But before doing anything, the validity of the hypothesis needs to be tested. The hypothesis is: lack of exhaust means poor IAQ means flu spreading. If this is not correct, a lot of money could be spent for no purpose.
In reviewing my notes from last weeks class, I see that moist air is the basis of climate control. My question is where and how does sensible and latent heat play a role in designing a space for thermal comfort?
Using the summer as context, moisture (latent heat) as well as sensible heat will flow through the building envelope (and be generated within a building) causing an increase in both indoor air temperature and relative humidity. Such an increase will tend to increase discomfort -- unless temperature and humidity are reduced by a cooling system, which will require energy to operate. The distinction between sensible and latent is important, otherwise a solution (such as insulation or a desiccant) may be used that does not address the real problem (temperature or moisture).
We discussed passive building design during our last lecture and I was wondering what are the pros and cons of passive building design as opposed to active or mechanical?
This will be covered in detail in the coming weeks, so an answer awaits.
What is LEEDS and how does a building qualify for a LEEDS green building award?
LEED (Leadership in Energy and Environmental Design) is a green building rating system developed by the US Green Building Council (USGBC). A building qualifies by amassing enough points in the rating system to achieve a defined level of "greenness." See www.usgbc.org for more information.
I've been thinking about the semester-long case study this past week.
This shows dedication (or suggests panic).
Thermal comfort inside of tall / cathedral ceilings interests me. As an example I thought about Notre Dame in Paris. I've always felt incredibly small inside that church. I have been inside the space in both the summer and winter months, and I've never felt uncomfortable in regard to temperature. I imagine buildings that have stone interiors must be extremely difficult to control as far as thermal comfort is concerned. OK, admittedly, I could have been so overwhelmed by the magnificent structure and the design of the building that I failed to take notice of my own comfort factor.
Anyway: For the project I thought about places that are here in Tallahassee which are somewhat similar to the idea of tall ceilings, stained glass, and almost gothic in a way. Right now, I'm leaning towards doing the case study on the Dodd Hall reading room at FSU. Anyone have any other suggestions?
The key is in what characteristics you want to study and which are present in Dodd Hall. Is the ability of a huge and grand space to distract from comfort concerns the main issue? Can Dodd Hall do that? Or is it the stained glass and comfort that is of interest? Can Dodd Hall do that? Or is it the effect of mass on comfort the key concern? The case study needs to have a clear focus -- and the method of analysis needs to be able to isolate on that focus.
Week 10: Spring Break
This page was last updated 26 January 2005.
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