Wednesday, 28 August 2013

Central Vs Window Air Conditioning - Which Works Best in San Jose?

An air conditioning unit is a must-have for every home in San Jose.  Most of the homes available on rent come with air conditioners installed in them. But, the recently-built houses do not have this facility. The tenant has to install one and that’s when his dilemma starts.

Questions such as which air conditioner would be the best, what would be the cost, will the internal wiring support the voltage configuration, how much will be the energy cost, and so on are foremost in every tenant’s mind. The decision-making period is the toughest, and the tenant has to explore the different options available in the market.

Types of air conditioners

1. Window air conditioners: These are units that sit in the window. They are usually held with the support of a piece of wood or metal board that protrudes from the window on the outer side. They just need to be plugged into any standard electrical outlet in the house.

2. Central air conditioners: These are units that spread coolness throughout the house through the ducts around the house interiors. Controlled by a central thermostat, these systems are best when you need to maintain perfect temperature throughout the house.

3. Portable air conditioners: These are systems that require no permanent installation. They are compact, mobile, and can be used to cool a certain area of the house. These units are best suited for areas with moderate levels of humidity. Most of the time, these units are chosen by people who need a supplement for their central air conditioners.  

In San Jose, we find people using window air conditioners in homes, while most offices are centrally air-conditioned. Centralized air conditioners are more common in older homes and in those built by homeowners for personal use.

With the recent housing boom, people looking for homes need to make a wise choice when it comes to choosing a most suitable air conditioner for the house. Most newly-built houses and condominiums do not come with built-in air conditioning systems and this is where a wise decision can go a long way.

Before a choice is made, we need to look at few basic differences between window air conditioner and a central system.

1. Expenses: In San Jose, buying a central air conditioning system can be a big investment in terms of the equipment required for the system, the ductwork required and the installation. In this comparison, the cost of a number of small units will be less than the cost of installing a new centralized air conditioning system.

2. Size: The size of the house or apartment you have moved into has a significant role to play here. If the residing area is not large, the window unit would be the best option. Spending the time money and energy in the installation of a centralized air conditioner may not be a good choice.

3. Efficiency: Statistics say that central air conditioners are more efficient than window units. A window air conditioner is about 20% less efficient that a central system.

4. Utility: In centralized air conditioners, the air-conditioning runs in the whole house, even if you are using only one room at a time. In the absence of a zoned system, you have no choice but to let the unit run, maintaining the same temperature throughout the house, whether it is required or not. In window units, you can simply switch off the air conditioner when you leave the room.

5. No leakage: As ductwork is absent in window air conditioners, there are lesser chances of wear and leaks. 

6. Repairs: Central HVAC systems are designed to deliver at least 10 years of service. With proper maintenance, they can last much longer. This is not so in the case of window air conditioners. The cost of repairs may prove to be more that the cost of buying a new system.

In San Jose, both types of systems work well. The decision on which type of unit to install depends on who you are – a homeowner or a tenant. There are pros and cons to both types of air conditioners and benefits to savings will depend upon your individual air conditioning needs.

Wednesday, 14 August 2013

How Relative Humidity Affects Indoor Air Quality?

We all know that humidity is vaporized water in the air. Relative humidity refers to the percentage of water vapor in the air at a given temperature, compared with water vapor that the air is capable of holding at that temperature. When the air at a certain temperature has all the water vapor it can hold at that temperature, the relative humidity is said to be 100%. When the relative humidity of a place is too high or too low, it can cause health problems, discomfort and generally less hygienic atmosphere. 

Indoor air quality

Environmental and energy researchers are always studying about the importance of indoor air quality. We all think healthy indoors means adequate ventilation, freshness in the air, control of pollutants and cleanliness. The list does not stop here. One important factor is the humidity levels in the rooms that can be the cause for inadequate hygiene.

The humidity of the air inside the house, if it is not maintained at optimal levels, can be a factor that has adverse affects on the health of the inmates. Maintaining the relative humidity of the air inside the house needs careful attention. 

Desired humidity levels

According to reports, the human body is said to be most comfortable when the relative humidity of the area ranges between 20 and 60%. The recommended average relative humidity for your indoors is 30 to 50%, when the outside temperature is 20°F or more. If the indoor relative humidity is above 60%, mold and mildew begin to form and these can pose quite a problem to the health of the inmates. Eventually, musty odor will start and the indoors will have a clammy feel.

On the other hand, when the relative humidity of the indoors is less than 30%, there is again the risk of health problems. Less than 30% of relative humidity can cause static electricity problems, irritation of the skin and dry eyes. The mucous membranes can start drying, which may reduce the person’s resistance towards upper respiratory illness.    

It is important that the inmates perceive ambient temperature based on the relative humidity of the place. In winter, the ambient temperature would be a between 69 and 78°F at a relative humidity of 30%. However, in summer, when the relative humidity is 60%, the thermostat will fall between 68 and 75°F.

Ways to improve indoor air quality

As the air remains inside the house longer, pollutants also stay longer. This kind if air infiltration differs from home to home. The air infiltration rates also change with weatherization, type of construction materials, and activities of the occupants. Infiltration rates are measured in air changes per hour (ACH), or the number of times the indoor air is replaced by outside air in an hour. The ACH rates differ from house to house and on daily basis. Usually, it is seen that older houses have ACH that averages from 1 to 2. New homes or older ones that are sealed may have an ACH of 5.

Remember, if the ACH rate is too low, the indoor air quality will be low.

Here are some tips to keep the indoor air quality high

  •  Open windows to provide CROSS ventilation and reduction of moisture and odors that normally rise from cooking and bathing.
  • Spot ventilation will help in reducing the amount of pollutants emitted in a specific area and also prevents their movement around the house.
  • Use a dehumidifier in summer and a humidifier in winter.
  • Use an air-to-air heat exchanger as it will mechanically ventilate and dehumidify houses in places where the climate is cold. These units can be installed as a part of your central cooling and heating systems.
  • Use furnace filters. These are coated with a viscous substance that allows the collection of dust, lint and fibers, preventing them from flowing into the room.
The humidity levels in San Jose are quite unpredictable. The relative humidity of this city ranges from a comfortable 38% to a very uncomfortable 98%.