Cooling Glass Sun Rooms

Sunrooms – Heating and Cooling
By Betty Stephens

Sunroom
This room may be called a solarium or conservatory. It is usually a glassed-in living space typically attached to the house and accessible from indoors designed to function as additional living area during mild weather but may be too hot or cold in the heart of summer or winter.

When a homeowner decides on a four season sunroom, the space must have a heating and cooling system. A space with most of the walls being windows needs proper temperature control. A four season sunroom should be comfortable all year long, even in the coldest winter months and hottest summer months. Since most homeowners already have central air conditioning in their home the sunroom can tap into the existing system. This is done by bringing ductwork into the sunroom and installing vents. The method is easy to keep the temperature of the room consistent with the rest of the house. A separate thermostat can also be installed and the sunroom’s temperature can be adjusted without affecting the rest of the house.
Need for Heating and Cooling
Since the need for heating and cooling is so variable throughout the year and even throughout the course of a day, independent temperature control in a room of this type is critical. If the thermostat that controls the home HVAC system is in the middle of the rest of the house and it is a mild, sunny day, the system will have very few calls for heating or cooling but the sunroom could be baking hot and will stay that way until the sun goes down.

Mini-split AC Units
While using existing ductwork is a very effective way to heat/cool a four season room, sometimes it is not an option. This method can be more difficult (and more costly) if the home is built on a concrete slab. There is another option for the homeowner is a mini-split air conditioning unit. They are slim and compact, wall-mounted systems. Mini-splits are usually installed high on a wall so that they are not at eye level, even though these units look quite stylish. The compressor is located outside of the sunroom with the tubing running behind the walls, completely out of site.

A mini-split it is a split system like most central air systems found in homes, with an inside air handler/evaporator unit and an outdoor condenser/compressor unit that are connected by refrigerant, power, and communications lines. One difference is it doesn’t use ductwork to distribute the air, but rather the wall mounted indoor unit handles moving the air. While these units can also be used to heat and cool an entire home very effectively, they’re almost tailor made for sunrooms. They are quiet, efficient, and powerful. These units are completely independent from the central HVAC system and as such can either keep the room perfectly comfortable or be completely switched off if the room isn’t used. They come in a range of options from cooling only non-inverter compressor units to hyper-heat high output heat pumps with an inverter compressor that is able to vary its output to match the exact need of the room.

Other Options
Other options for heating and cooling is using a PTAC unit (called a Hotel unit) which is similar to what is seen in hotel rooms, or a portable air conditioning units. Homeowners can have radiant floor heating or base board heating installed. However, they only heat the sunroom and won’t provide a cooling mechanism.

Location of Sunroom
Deciding the best location for the sunroom room is the first step when planning a glass or screen addition. In northern climates, a southern exposure is best because it receives the most light each day.

In the South, a southern exposure means additional cooling is necessary, which could be costly.

An eastern exposure eases cooling by providing sun in the morning and shade the rest of the day, but not so great for after work.

A western exposure will expose you to harsh afternoon sun that needs to be shaded.

A northern exposure provides lower levels of light and partial shade most of the day. In the North, this can cause the room to be too cool and damp, but it can work fine in the South.