Radiant heating -cooling

Nron_9

The science is always changing and adapting to enviromental standards take a look at the artical at pm engeeneering
http://www.pmengineer.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2732,135227,00.html

GMcD

Yeah, great article ; )

Hydronics, man, that where the future is. No more wasted energy with "all-air" systems. Spend $$ on the envelopes and use semi-passsive hydronic systems with dedicated outdoor air systems or hybrid natural ventilation systems depending on the local climate.

Constantin

Hmmm, the author seems familiar... ;-)

Geoff, that's a great, concise primer for folk to consider when they design their buildings. I would have found radiant cooling and heating a pretty neat option, if there had been more experience with it over here.

I also like your approach of extracting excess heat from one part of the structure and dumping it where it is needed, thus creating an efficient internal heat pump.

Perhaps some day in the future I will be able to use a two stage thermostat to cool my home with the radiant floor to start and with air as a backup. Combined with a large buffer tank or even a bsement slab, it could make very efficient use of external condensors, etc. Ah, what interesting times that lie ahead...

GMcD

Laws of physics

They are universal. These large scale and small scale radiant slab cooling/heating systems have been in operation for over 20 years in Europe so it's not black magic. I was fortunate enough to spend some time with Herr Professor Bruno Keller from the ETHZ in Zurich to tour myself and another fellow through the Batiso (constant temperature) buildings that he has designed and have been operating for some time. Simple concept, easy to do, and extremely low energy use. We have some of these types of systems operating now in my neighborhood, so if anyone wants to see them, they don't have to get to Switzerland anymore. But the North American building design industry hasn't really got the concept of integrated building design and applied "building physics". It's everybody for himself, selling a particular component, or system in isolation. Capital costs in North America always seem to override life cycle costs because of the short sighted "next quarter performance" driven economy.

Google search "oil peak" and try thinking what might lay ahead 10, even 5 years from now when other world economies start overconsuming resources....new buildings must be designed to be future-proof if we want any kind of reasonable operation 20 years from now when the next generation inherits the building stock we are designing now.

jerry scharf_2

tell me about the MRT sensors

Geoff,

Where did you get them and what kind of interface do they have. Always looking for new and interesting inputs for my control system.

jerry

GMcD

Mean Radiant Temperature sensors

We haven't used any yet due to lack of them in North America. All of the radiant slab projects I've designed use a combination of a regular thermistor space temperature sensor and imbedded in-slab temperature sensors to get average readings for each zone and space to reset the slab water temperature as needed. The system performance relies mainly on a high performance glass and envelope to reduce the transient loads to a minimum, so the whole interior acts more like a steady-state thermal zone. The small transients caused by people and equipment in each room are not enough to cause any large comfort/temperature differences between rooms or zones. The air system (still required for ventilation- but strictly ventilation only, so it's a minimal system) can be used to deal with room to room or zone to zone thermal load variations.

Siemens makes some commercial MRT sensors in Europe, but they are not available over here, and Yamatake in Japan makes some too, but, not available in North America.

North America is lagging far behind in terms of building design and building systems design and operation compared to other areas of the world. Watch out for the new building boom in China- they are already developing Batiso style high rise apartment buildings. I know of one local (Burnaby, BC) development of high rise concrete apartments (dormitories) with radiant slabs and heat recovery ventlators, but are there any others in North America?

Uni R

Batiso Style?

Geoff, what does Batiso style mean?

GMcD

Batiso style

Batiso = Batiment Isotherm = constant temperature building. A building design that uses a high performance envelope to keep climate variations/transients outside the building, so the whole interior space can be maintained at a constant temperature, usually using thermal mass systems - radiant heating/cooling slabs, passive solar heat, diurnal temperature differences, etc.

The term "Batiso" is now patented by the Zent-Frenger folks in Switzerland for their pre-fabricated pex tubes in re-bar mesh assemblies. The term "Batiso" was coined in the 1980's when the Geilinger Company in Switzerland was developing the Visionwall type suspended film window systems, and the first buildings using radiant slab systems with Visionwall type glazing systems were used to create the first "constant temperature buildings".

Mike T., Swampeast MO

General Motors?

Am pretty certain that their climate control systems use a MRT sensor mounted in the dashboard--looks like half of a little black sphere

GMcD

MRT for autos

Yes, many of the auto makers use them for window defogging and heater control. Unfortunately they don't translate well to standard wall mounted, or surface mounted devices with HVAC industry standard outputs. One could "MacGyver" one together though....

Mike T., Swampeast MO

Are those MRT sensors (the ones not available here) based on "black ball thermometers" where a temp sensor is placed inside a hollow (usually copper) sphere painted black?

If so, am guessing that such a sensor is only good when the MRT is higher than the room air temp as the inside temp would rather rapidly assume the temp of the air surrounding. Correct? Am guessing further that the goal is to maintain a MRT a bit higher than the air temp. Correct?

GMcD

Nope and nope

MRT sensors like the Yamatake and the Siemens sensors are based on infrared sensors that sense cooler or warmer MRT's. In Europe, where there is a lot of radiant cooling and heating systems used commercially, the MRT sensors work for both heating and cooling sensing. I believe they use the same type of sensor/device used in your regular everyday hand-held infrared surface temperature sensor that most of us "radiant guys" have in the toolkit. The goals are to maintain the MRT cooler in summertime, and warmer in wintertime. But, you have to remember that the primary thermal control device is a high performance window with good solar control so the transient heating and cooling loads are kept outside the building in the first place. Typical radiant cooling systems use radiant ceiling surface temperatures around 17C (63F) at the coolest and 26C (78.5F) at the warmest to maintain a room "resultant temperature of 24C (75F) (using standard German room design criteria as an example)

Mike T., Swampeast MO

IR Sensor with \"Fisheye\" View

Do understand the "super window" concept. I just hope they can perform that well for many, many decades. My 1903 windows with storms may not be "super" but they're reasonable and can stay that way until I'm dust.

Uni R

Must be a franconym...

Thanks Geoff